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 A261611 #5 Aug 26 2015 12:19:18
%S A261611 1,2,2,2,2,4,6,6,6,8,12,14,14,16,22,28,30,32,40,50,56,60,70,86,98,106,
%T A261611 120,144,166,180,200,234,270,296,324,372,428,472,514,580,664,736,800,
%U A261611 890,1010,1124,1222,1346,1514,1684,1834,2008,2240,2488,2712,2956
%N A261611 Expansion of Product_{k>=0} (1 + x^(4*k+1))/(1 - x^(4*k+1)).
%C A261611 In general, if a > 0, b > 0, GCD(a,b) = 1 and g.f. = Product_{k>=0} (1 + x^(a*k+b))/(1 - x^(a*k+b)), then a(n) ~ Gamma(b/a) * a^(b/(2*a) - 1/2) * Pi^(b/a - 1) * exp(Pi*sqrt(n/a)) / (2^(2*b/a + 1) * n^(b/(2*a) + 1/2)).
%F A261611 a(n) ~ exp(Pi*sqrt(n)/2) * Gamma(1/4) / (2^(9/4) * Pi^(3/4) * n^(5/8)).
%t A261611 nmax = 60; CoefficientList[Series[Product[(1 + x^(4*k+1))/(1 - x^(4*k+1)), {k, 0, nmax}], {x, 0, nmax}], x]
%Y A261611 Cf. A015128, A080054, A261610.
%K A261611 nonn
%O A261611 0,2
%A A261611 _Vaclav Kotesovec_, Aug 26 2015