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 A261650 #4 Aug 28 2015 05:07:14
%S A261650 1,4,8,12,16,24,40,60,80,104,144,204,272,344,440,584,768,968,1200,
%T A261650 1516,1936,2424,2968,3644,4528,5596,6800,8216,10000,12184,14688,17564,
%U A261650 21056,25320,30272,35912,42576,50616,60024,70728,83136,97896,115200,134924,157504
%N A261650 Expansion of Product_{k>=0} ((1+x^(4*k+1))/(1-x^(4*k+1)))^2.
%F A261650 a(n) ~ exp(Pi*sqrt(n/2)) * 2^(3/2) * Gamma(1/4)^2 / (16 * Pi^(3/2) * sqrt(n)).
%t A261650 nmax=60; CoefficientList[Series[Product[((1+x^(4*k+1))/(1-x^(4*k+1)))^2,{k,0,nmax}],{x,0,nmax}],x]
%Y A261650 Cf. A015128, A156616, A080054, A007096, A261611, A261652.
%K A261650 nonn
%O A261650 0,2
%A A261650 _Vaclav Kotesovec_, Aug 28 2015