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 A171799 #2 Mar 30 2012 18:37:20
%S A171799 1,2,20,648,78608,37949472,74258600000,589859028828288,
%T A171799 18957096840069579008,2455889836782322072945152,
%U A171799 1278835681226410156250000000000,2671465293024628033252951422140418048
%N A171799 O.g.f.: Sum_{n>=0} 2^(n^2)*x^n/(1 - 2^n*x)^n.
%F A171799 a(n) = 2^n*(2^n + 1)^(n-1) for n>0 with a(0)=1.
%e A171799 G.f.: A(x) = 1 + 2*x + 20*x^2 + 648*x^3 + 78608*x^4 +...
%e A171799 A(x) = 1 + 2*x/(1-2*x) + 2^4*x^2/(1-2^2*x)^2 + 2^9*x^3/(1-2^3*x)^3 +...
%o A171799 (PARI) {a(n)=polcoeff(sum(m=0,n,2^(m^2)*x^m/(1-2^m*x+x*O(x^n))^m),n)}
%o A171799 (PARI) {a(n)=if(n==0,1,2^n*(2^n+1)^(n-1))}
%Y A171799 Cf. A171801, A171800, A136516.
%K A171799 nonn
%O A171799 0,2
%A A171799 _Paul D. Hanna_, Jan 20 2010