A014070 a(n) = binomial(2^n, n).
1, 2, 6, 56, 1820, 201376, 74974368, 94525795200, 409663695276000, 6208116950265950720, 334265867498622145619456, 64832175068736596027448301568, 45811862025512780638750907861652480, 119028707533461499951701664512286557511680
Offset: 0
Links
- Vincenzo Librandi, Table of n, a(n) for n = 0..60
Crossrefs
Programs
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Magma
[Binomial(2^n, n): n in [0..25]]; // Vincenzo Librandi, Sep 13 2016
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Maple
A014070:= n-> binomial(2^n,n); seq(A014070(n), n=0..20); # G. C. Greubel, Mar 14 2021
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Mathematica
Table[Binomial[2^n,n],{n,0,20}] (* Vladimir Joseph Stephan Orlovsky, Mar 03 2011 *)
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PARI
a(n)=binomial(2^n,n)
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PARI
/* G.f. A(x) as Sum of Series: */ a(n)=polcoeff(sum(k=0,n,log(1+2^k*x +x*O(x^n))^k/k!),n) \\ Paul D. Hanna, Dec 28 2007
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PARI
{a(n) = (1/n!) * sum(k=0,n, stirling(n, k, 1) * 2^(n*k) )} for(n=0,20,print1(a(n),", ")) \\ Paul D. Hanna, Feb 05 2023
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Sage
[binomial(2^n, n) for n in (0..20)] # G. C. Greubel, Mar 14 2021
Formula
G.f.: A(x) = Sum_{n>=0} log(1 + 2^n*x)^n / n!. - Paul D. Hanna, Dec 28 2007
a(n) = (1/n!) * Sum_{k=0..n} Stirling1(n, k) * 2^(n*k). - Paul D. Hanna, Feb 05 2023
From Vaclav Kotesovec, Jul 02 2016: (Start)
a(n) ~ 2^(n^2) / n!.
a(n) ~ 2^(n^2 - 1/2) * exp(n) / (sqrt(Pi) * n^(n+1/2)).
(End)
Comments