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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Double exponential function</span></span>
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<p>A <b>double exponential</b> function is a <a href="Constant_(mathematics)" title="Constant (mathematics)">constant</a> raised to the power of an <a href="Exponentiation" title="Exponentiation">exponential function</a>. The general formula is <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle f(x)=a^{b^{x}}=a^{(b^{x})}}">
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<annotation encoding="application/x-tex">{\displaystyle f(x)=a^{b^{x}}=a^{(b^{x})}}</annotation>
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</math></span><img src="./6d686647ff4b19b1669aa6bb6d97fa552cb258dc.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:18.084ex; height:3.343ex;" alt="{\displaystyle f(x)=a^{b^{x}}=a^{(b^{x})}}" loading="lazy"></span> (where <i>a</i>&gt;1 and <i>b</i>&gt;1), which grows much more quickly than an exponential function. For example, if <i>a</i> = <i>b</i> = 10:
</p>
<ul><li><i>f</i>(x) = 10<sup>10<sup>x</sup></sup></li>
<li><i>f</i>(0) = 10</li>
<li><i>f</i>(1) = 10<sup>10</sup></li>
<li><i>f</i>(2) = 10<sup>100</sup> = <a href="Googol" title="Googol">googol</a></li>
<li><i>f</i>(3) = 10<sup>1000</sup></li>
<li><i>f</i>(100) = 10<sup>10<sup>100</sup></sup> = <a href="Googolplex" title="Googolplex">googolplex</a>.</li></ul>
<p><a href="Factorial" title="Factorial">Factorials</a> grow faster than exponential functions, but much more slowly than double exponential functions. However, <a href="Tetration" title="Tetration">tetration</a> and the <a href="Ackermann_function" title="Ackermann function">Ackermann function</a> grow faster. See <a href="Big_O_notation" title="Big O notation">Big O notation</a> for a comparison of the rate of growth of various functions.
</p><p>The inverse of the double exponential function is the <a href="Logarithm#double_logarithm" title="Logarithm">double logarithm</a> log(log(<i>x</i>)). The complex double exponential function is <a href="Entire_function" title="Entire function">entire</a>, because it is the composition of two entire functions <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle f(x)=a^{x}=e^{x\ln a}}">
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<annotation encoding="application/x-tex">{\displaystyle f(x)=a^{x}=e^{x\ln a}}</annotation>
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</math></span><img src="./6b5b0907c4a3cd0ce4fd344c70d8c7088b7177cf.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:18.288ex; height:3.176ex;" alt="{\displaystyle f(x)=a^{x}=e^{x\ln a}}" loading="lazy"></span> and <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle g(x)=b^{x}=e^{x\ln b}}">
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<annotation encoding="application/x-tex">{\displaystyle g(x)=b^{x}=e^{x\ln b}}</annotation>
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</math></span><img src="./3fa891946e2ec295e861c876d9cf50223c6ff1c5.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:17.729ex; height:3.176ex;" alt="{\displaystyle g(x)=b^{x}=e^{x\ln b}}" loading="lazy"></span>.
</p>
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<div class="mw-heading mw-heading2"><h2 id="Double_exponential_sequences">Double exponential sequences</h2></div>
<p>A sequence of positive integers (or real numbers) is said to have <i>double exponential rate of growth</i> if the function giving the <span class="texhtml mvar" style="font-style:italic;">n</span>th term of the sequence is bounded above and below by double exponential functions of <span class="texhtml mvar" style="font-style:italic;">n</span>.
Examples include
</p>
<ul><li>The <a href="Fermat_number" title="Fermat number">Fermat numbers</a> <span class="mwe-math-element mwe-math-element-block"><span class="mwe-math-mathml-display mwe-math-mathml-a11y" style="display: none;"><math display="block" xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle F(m)=2^{2^{m}}+1}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>F</mi>
<mo stretchy="false">(</mo>
<mi>m</mi>
<mo stretchy="false">)</mo>
<mo>=</mo>
<msup>
<mn>2</mn>
<mrow class="MJX-TeXAtom-ORD">
<msup>
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<annotation encoding="application/x-tex">{\displaystyle F(m)=2^{2^{m}}+1}</annotation>
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</math></span></span></li>
<li>The harmonic primes: The primes <i>p</i>, in which the sequence <span class="nowrap">1/2 + 1/3 + 1/5 + 1/7 + ⋯ + 1/<i>p</i></span> exceeds 0, 1, 2, 3, …<div class="paragraphbreak" style="margin-top:0.5em"></div>The first few numbers, starting with 0, are 2, 5, 277, 5195977, ... (sequence <span class="nowrap external"><a href="https://oeis.org/A016088" class="extiw external" title="oeis:A016088">A016088</a></span> in the <a href="On-Line_Encyclopedia_of_Integer_Sequences" title="On-Line Encyclopedia of Integer Sequences">OEIS</a>)</li>
<li>The <a href="Double_Mersenne_number" title="Double Mersenne number">Double Mersenne numbers</a> <span class="mwe-math-element mwe-math-element-block"><span class="mwe-math-mathml-display mwe-math-mathml-a11y" style="display: none;"><math display="block" xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle MM(p)=2^{2^{p}-1}-1}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>M</mi>
<mi>M</mi>
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<annotation encoding="application/x-tex">{\displaystyle MM(p)=2^{2^{p}-1}-1}</annotation>
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</math></span></span></li>
<li>The elements of <a href="Sylvester's_sequence" title="Sylvester's sequence">Sylvester's sequence</a> (sequence <span class="nowrap external"><a href="https://oeis.org/A000058" class="extiw external" title="oeis:A000058">A000058</a></span> in the <a href="On-Line_Encyclopedia_of_Integer_Sequences" title="On-Line Encyclopedia of Integer Sequences">OEIS</a>) <span class="mwe-math-element mwe-math-element-block"><span class="mwe-math-mathml-display mwe-math-mathml-a11y" style="display: none;"><math display="block" xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle s_{n}=\left\lfloor E^{2^{n+1}}+{\frac {1}{2}}\right\rfloor }">
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<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
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<mi>E</mi>
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<annotation encoding="application/x-tex">{\displaystyle s_{n}=\left\lfloor E^{2^{n+1}}+{\frac {1}{2}}\right\rfloor }</annotation>
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</math></span></span> where <i>E</i> ≈ 1.264084735305302 is Vardi's constant (sequence <span class="nowrap external"><a href="https://oeis.org/A076393" class="extiw external" title="oeis:A076393">A076393</a></span> in the <a href="On-Line_Encyclopedia_of_Integer_Sequences" title="On-Line Encyclopedia of Integer Sequences">OEIS</a>).</li>
<li>The number of <a href="Arity" title="Arity"><i>k</i>-ary</a> <a href="Boolean_function" title="Boolean function">Boolean functions</a>: <span class="mwe-math-element mwe-math-element-block"><span class="mwe-math-mathml-display mwe-math-mathml-a11y" style="display: none;"><math display="block" xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle 2^{2^{k}}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<msup>
<mn>2</mn>
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<mi>k</mi>
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<annotation encoding="application/x-tex">{\displaystyle 2^{2^{k}}}</annotation>
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</math></span></span></li>
<li>The prime numbers 2, 11, 1361, ... (sequence <span class="nowrap external"><a href="https://oeis.org/A051254" class="extiw external" title="oeis:A051254">A051254</a></span> in the <a href="On-Line_Encyclopedia_of_Integer_Sequences" title="On-Line Encyclopedia of Integer Sequences">OEIS</a>) <span class="mwe-math-element mwe-math-element-block"><span class="mwe-math-mathml-display mwe-math-mathml-a11y" style="display: none;"><math display="block" xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle a(n)=\left\lfloor A^{3^{n}}\right\rfloor }">
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<annotation encoding="application/x-tex">{\displaystyle a(n)=\left\lfloor A^{3^{n}}\right\rfloor }</annotation>
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</math></span></span> where <i>A</i> ≈ 1.306377883863 is <a href="Mills'_constant" title="Mills' constant">Mills' constant</a>.</li></ul>
<p><a href="Alfred_Aho" title="Alfred Aho">Aho</a> and <a href="Neil_Sloane" title="Neil Sloane">Sloane</a> observed that in several important <a href="Integer_sequence" title="Integer sequence">integer sequences</a>, each term is a constant plus the square of the previous term. They show that such sequences can be formed by rounding to the nearest integer the values of a double exponential function with middle exponent 2.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup>
Ionaşcu and Stănică describe some more general sufficient conditions for a sequence to be the floor of a double exponential sequence plus a constant.<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>
</p>
<div class="mw-heading mw-heading2"><h2 id="Applications">Applications</h2></div>
<div class="mw-heading mw-heading3"><h3 id="Algorithmic_complexity">Algorithmic complexity</h3></div>
<p>In <a href="Computational_complexity_theory" title="Computational complexity theory">computational complexity theory</a>, <a href="2-EXPTIME" title="2-EXPTIME">2-EXPTIME</a> is the class of decision problems solvable in double exponential time. It is equivalent to AEXPSPACE, the set of decision problems solvable by an <a href="Alternating_Turing_machine" title="Alternating Turing machine">alternating Turing machine</a> in exponential space, and is a superset of <a href="EXPSPACE" title="EXPSPACE">EXPSPACE</a>.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> An example of a problem in 2-EXPTIME that is not in EXPTIME is the problem of proving or disproving statements in <a href="Presburger_arithmetic" title="Presburger arithmetic">Presburger arithmetic</a>.<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup>
</p><p>In some other problems in the design and analysis of algorithms, double exponential sequences are used within the design of an algorithm rather than in its analysis. An example is <a href="Chan's_algorithm" title="Chan's algorithm">Chan's algorithm</a> for computing <a href="Convex_hull" title="Convex hull">convex hulls</a>, which performs a sequence of computations using test values <i>h</i><sub><i>i</i></sub>&nbsp;=&nbsp;2<sup>2<sup><i>i</i></sup></sup> (estimates for the eventual output size), taking time O(<i>n</i>&nbsp;log&nbsp;<i>h</i><sub><i>i</i></sub>) for each test value in the sequence. Because of the double exponential growth of these test values, the time for each computation in the sequence grows singly exponentially as a function of <i>i</i>, and the total time is dominated by the time for the final step of the sequence. Thus, the overall time for the algorithm is O(<i>n</i>&nbsp;log&nbsp;<i>h</i>) where <i>h</i> is the actual output size.<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup>
</p>
<div class="mw-heading mw-heading3"><h3 id="Number_theory">Number theory</h3></div>
<p>Some <a href="Number_theory" title="Number theory">number theoretical</a> bounds are double exponential. <a href="Odd_perfect_number" class="mw-redirect" title="Odd perfect number">Odd perfect numbers</a> with <i>n</i> distinct prime factors are known to be at most <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle 2^{4^{n}}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<msup>
<mn>2</mn>
<mrow class="MJX-TeXAtom-ORD">
<msup>
<mn>4</mn>
<mrow class="MJX-TeXAtom-ORD">
<mi>n</mi>
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<annotation encoding="application/x-tex">{\displaystyle 2^{4^{n}}}</annotation>
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</math></span><img src="./69f0fa63c02614549b40f2bc329f4880fad12904.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:3.182ex; height:2.676ex;" alt="{\displaystyle 2^{4^{n}}}" loading="lazy"></span>, a result of Nielsen (2003).<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup>
</p><p>The maximal volume of a <a href="Polytope" title="Polytope">polytope</a> in a <i>d</i>-dimensional <a href="Integer_lattice" title="Integer lattice">integer lattice</a> with <i>k</i> ≥ 1 <a href="Integer_points_in_convex_polyhedra" title="Integer points in convex polyhedra">interior lattice points</a> is at most
</p>
<dl><dd><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle k\cdot (8d)^{d}\cdot 15^{d\cdot 2^{2d+1}},}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>k</mi>
<mo>⋅<!-- ⋅ --></mo>
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<mn>8</mn>
<mi>d</mi>
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<mo stretchy="false">)</mo>
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<mo>,</mo>
</mstyle>
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<annotation encoding="application/x-tex">{\displaystyle k\cdot (8d)^{d}\cdot 15^{d\cdot 2^{2d+1}},}</annotation>
</semantics>
</math></span><img src="./51fcadf3346461223fec0229c790f763c89d433b.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:18.427ex; height:3.509ex;" alt="{\displaystyle k\cdot (8d)^{d}\cdot 15^{d\cdot 2^{2d+1}},}" loading="lazy"></span></dd></dl>
<p>a result of Pikhurko (2001).<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup>
</p><p>The <a href="Largest_known_prime_number" title="Largest known prime number">largest known prime number</a> in the electronic era has grown roughly as a double exponential function of the year since <a href="J._C._P._Miller" title="J. C. P. Miller">Miller</a> and <a href="David_Wheeler_(computer_scientist)" title="David Wheeler (computer scientist)">Wheeler</a> found a 79-digit prime on <a href="EDSAC" title="EDSAC">EDSAC</a>1 in 1951.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup>
</p>
<div class="mw-heading mw-heading3"><h3 id="Theoretical_biology">Theoretical biology</h3></div>
<p>In <a href="Population_dynamics" title="Population dynamics">population dynamics</a> the growth of human population is sometimes supposed to be double exponential. Varfolomeyev and Gurevich<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> experimentally fit
</p>
<dl><dd><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle N(y)=375.6\cdot 1.00185^{1.00737^{y-1000}}\,}">
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<mi>N</mi>
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<mi>y</mi>
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<mo>=</mo>
<mn>375.6</mn>
<mo>⋅<!-- ⋅ --></mo>
<msup>
<mn>1.00185</mn>
<mrow class="MJX-TeXAtom-ORD">
<msup>
<mn>1.00737</mn>
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<annotation encoding="application/x-tex">{\displaystyle N(y)=375.6\cdot 1.00185^{1.00737^{y-1000}}\,}</annotation>
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</math></span><img src="./eafde06aaa161da082dbb58935ff71543ec4b369.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:33.268ex; height:3.509ex;" alt="{\displaystyle N(y)=375.6\cdot 1.00185^{1.00737^{y-1000}}\,}" loading="lazy"></span></dd></dl>
<p>where <i>N</i>(<i>y</i>) is the population in millions in year <i>y</i>.
</p>
<div class="mw-heading mw-heading3"><h3 id="Physics">Physics</h3></div>
<p>In the <a href="Toda_oscillator" title="Toda oscillator">Toda oscillator</a> model of <a href="Self-pulsation" title="Self-pulsation">self-pulsation</a>, the logarithm of amplitude varies exponentially with time (for large amplitudes), thus the amplitude varies as double exponential function of time.<sup id="cite_ref-kouz_10-0" class="reference"><a href="#cite_note-kouz-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup>
</p><p>Dendritic <a href="Macromolecule" title="Macromolecule">macromolecules</a> have been observed to grow in a doubly-exponential fashion.<sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup>
</p>
<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>
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/* end https://en.wikipedia.org/ */
</style><cite id="CITEREFAhoSloane1973" class="citation cs2"><a href="Alfred_Aho" title="Alfred Aho">Aho, A. V.</a>; <a href="N._J._A._Sloane" class="mw-redirect" title="N. J. A. Sloane">Sloane, N. J. A.</a> (1973), <a rel="nofollow" class="external text" href="http://neilsloane.com/doc/doubly.html">"Some doubly exponential sequences"</a>, <i><a href="Fibonacci_Quarterly" title="Fibonacci Quarterly">Fibonacci Quarterly</a></i>, <b>11</b>: <span class="nowrap">429–</span>437</cite>.</span>
</li>
<li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><cite id="CITEREFIonaşcuStănică2004" class="citation cs2">Ionaşcu, Eugen-Julien; Stănică, Pantelimon (2004), <a rel="nofollow" class="external text" href="http://faculty.nps.edu/pstanica/research/AMUC04.pdf">"Effective asymptotics for some nonlinear recurrences and almost doubly-exponential sequences"</a> <span class="cs1-format">(PDF)</span>, <i>Acta Mathematica Universitatis Comenianae</i>, <b>LXXIII</b> (1): <span class="nowrap">75–</span>87</cite>.</span>
</li>
<li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><a href="Christos_Papadimitriou" title="Christos Papadimitriou">Christos Papadimitriou</a>, Computational Complexity (1994), <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a>&nbsp;<bdi>978-0-201-53082-7</bdi>. Section 20.1, corollary 3, page 495.</span>
</li>
<li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text"><a href="Michael_J._Fischer" title="Michael J. Fischer">Fischer, M. J.</a>, and <a href="Michael_O._Rabin" title="Michael O. Rabin">Michael O. Rabin</a>, 1974, "<a rel="nofollow" class="external text" href="http://www.lcs.mit.edu/publications/pubs/ps/MIT-LCS-TM-043.ps">"Super-Exponential Complexity of Presburger Arithmetic.</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20060915010325/http://www.lcs.mit.edu/publications/pubs/ps/MIT-LCS-TM-043.ps">Archived</a> 2006-09-15 at the <a href="Wayback_Machine" title="Wayback Machine">Wayback Machine</a>" <i>Proceedings of the SIAM-AMS Symposium in Applied Mathematics Vol. 7</i>: 27–41</span>
</li>
<li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text"><cite id="CITEREFChan1996" class="citation cs2"><a href="Timothy_M._Chan" title="Timothy M. Chan">Chan, T. M.</a> (1996), "Optimal output-sensitive convex hull algorithms in two and three dimensions", <i><a href="Discrete_and_Computational_Geometry" class="mw-redirect" title="Discrete and Computational Geometry">Discrete and Computational Geometry</a></i>, <b>16</b> (4): <span class="nowrap">361–</span>368, <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1007%2FBF02712873">10.1007/BF02712873</a></span>, <a href="MR_(identifier)" class="mw-redirect" title="MR (identifier)">MR</a>&nbsp;<a rel="nofollow" class="external text" href="https://mathscinet.ams.org/mathscinet-getitem?mr=1414961">1414961</a></cite></span>
</li>
<li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text"><cite id="CITEREFNielsen2003" class="citation cs2">Nielsen, Pace P. (2003), <a rel="nofollow" class="external text" href="http://www.integers-ejcnt.org/vol3.html">"An upper bound for odd perfect numbers"</a>, <i>INTEGERS: The Electronic Journal of Combinatorial Number Theory</i>, <b>3</b>: A14</cite>.</span>
</li>
<li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text"><cite id="CITEREFPikhurko2001" class="citation cs2">Pikhurko, Oleg (2001), "Lattice points in lattice polytopes", <i><a href="Mathematika" title="Mathematika">Mathematika</a></i>, <b>48</b> (<span class="nowrap">1–</span>2): <span class="nowrap">15–</span>24, <a href="ArXiv_(identifier)" class="mw-redirect" title="ArXiv (identifier)">arXiv</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://arxiv.org/abs/math/0008028">math/0008028</a></span>, <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2000math......8028P">2000math......8028P</a>, <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1112%2Fs0025579300014339">10.1112/s0025579300014339</a></cite></span>
</li>
<li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</a></b></span> <span class="reference-text"><cite id="CITEREFMillerWheeler1951" class="citation cs2">Miller, J. C. P.; Wheeler, D. J. (1951), "Large prime numbers", <i><a href="Nature_(journal)" title="Nature (journal)">Nature</a></i>, <b>168</b> (4280): 838, <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1951Natur.168..838M">1951Natur.168..838M</a>, <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1038%2F168838b0">10.1038/168838b0</a></span></cite>.</span>
</li>
<li id="cite_note-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-9">^</a></b></span> <span class="reference-text"><cite id="CITEREFVarfolomeyevGurevich2001" class="citation cs2">Varfolomeyev, S. D.; Gurevich, K. G. (2001), "The hyperexponential growth of the human population on a macrohistorical scale", <i>Journal of Theoretical Biology</i>, <b>212</b> (3): <span class="nowrap">367–</span>372, <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2001JThBi.212..367V">2001JThBi.212..367V</a>, <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1006%2Fjtbi.2001.2384">10.1006/jtbi.2001.2384</a>, <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a>&nbsp;<a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/11829357">11829357</a></cite>.</span>
</li>
<li id="cite_note-kouz-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-kouz_10-0">^</a></b></span> <span class="reference-text"><cite id="CITEREFKouznetsovBissonLiUeda2007" class="citation cs2">Kouznetsov, D.; Bisson, J.-F.; Li, J.; Ueda, K. (2007), <a rel="nofollow" class="external text" href="http://www.iop.org/EJ/abstract/-search=15823442.1/1751-8121/40/9/016">"Self-pulsing laser as oscillator Toda: Approximation through elementary functions"</a>, <i><a href="Journal_of_Physics_A" title="Journal of Physics A">Journal of Physics A</a></i>, <b>40</b> (9): <span class="nowrap">1–</span>18, <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2007JPhA...40.2107K">2007JPhA...40.2107K</a>, <a href="CiteSeerX_(identifier)" class="mw-redirect" title="CiteSeerX (identifier)">CiteSeerX</a>&nbsp;<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.535.5379">10.1.1.535.5379</a></span>, <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1088%2F1751-8113%2F40%2F9%2F016">10.1088/1751-8113/40/9/016</a>, <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a>&nbsp;<a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:53330023">53330023</a></cite>.</span>
</li>
<li id="cite_note-11"><span class="mw-cite-backlink"><b><a href="#cite_ref-11">^</a></b></span> <span class="reference-text"><cite id="CITEREFKawaguchiWalkerWilkinsMoore1995" class="citation journal cs1">Kawaguchi, Tohru; Walker, Kathleen L.; Wilkins, Charles L.; Moore, Jeffrey S. (1995). "Double Exponential Dendrimer Growth". <i><a href="Journal_of_the_American_Chemical_Society" title="Journal of the American Chemical Society">Journal of the American Chemical Society</a></i>. <b>117</b> (8): <span class="nowrap">2159–</span>2165. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1021%2Fja00113a005">10.1021/ja00113a005</a>.</cite></span>
</li>
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