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 A261616 #6 Aug 26 2015 16:17:02
%S A261616 1,2,3,4,7,10,13,18,26,34,44,58,76,96,123,156,196,244,304,374,461,566,
%T A261616 690,836,1015,1224,1470,1762,2110,2512,2987,3542,4191,4944,5825,6842,
%U A261616 8025,9392,10971,12788,14891,17300,20068,23242,26883,31034,35787,41204
%N A261616 Expansion of Product_{k>=0} 1/(1 - x^(3*k+1))^2.
%C A261616 Self-convolution of A035382.
%C A261616 In general, if a > 0, b > 0, GCD(a,b) = 1 and g.f. = Product_{k>=0} 1/(1 - x^(a*k+b))^2, then a(n) ~ Gamma(b/a)^2 * a^(b/a - 3/4) * exp(2*Pi*sqrt(n/(3*a))) * Pi^(2*b/a - 2) / (4 * 3^(b/a - 1/4) * n^(b/a + 1/4)).
%F A261616 a(n) ~ exp(2*Pi*sqrt(n)/3) * Gamma(1/3)^2 / (4 * sqrt(3) * Pi^(4/3) * n^(7/12)).
%t A261616 nmax = 60; CoefficientList[Series[Product[1/(1 - x^(3*k+1))^2, {k, 0, nmax}], {x, 0, nmax}], x]
%Y A261616 Cf. A022567, A035382, A261610, A261612, A261615.
%K A261616 nonn
%O A261616 0,2
%A A261616 _Vaclav Kotesovec_, Aug 26 2015