This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A171801 #2 Mar 30 2012 18:37:20
%S A171801 1,4,56,2448,379168,223096896,514098000000,4691436926959872,
%T A171801 170097530401558168064,24520599890836361905701888,
%U A171801 14055963692387060312500000000000
%N A171801 O.g.f.: Sum_{n>=0} (n+1)*2^(n^2)*x^n/(1 - 2^n*x)^n.
%F A171801 a(n) = 2^n * ((n+1)*2^n + 2) * (2^n + 1)^(n-2) for n>0 with a(0)=1.
%e A171801 G.f.: A(x) = 1 + 4*x + 56*x^2 + 2448*x^3 + 379168*x^4 +...
%e A171801 A(x) = 1 + 2*2*x/(1-2*x) + 3*2^4*x^2/(1-2^2*x)^2 + 4*2^9*x^3/(1-2^3*x)^3 +...
%o A171801 (PARI) {a(n)=polcoeff(sum(m=0,n,(m+1)*2^(m^2)*x^m/(1-2^m*x+x*O(x^n))^m),n)}
%o A171801 (PARI) {a(n)=if(n==0,1,2^n*((n+1)*2^n + 2)*(2^n + 1)^(n-2))}
%Y A171801 Cf. A171799, A171800.
%K A171801 nonn
%O A171801 0,2
%A A171801 _Paul D. Hanna_, Jan 20 2010