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 A261633 #4 Aug 28 2015 03:15:24
%S A261633 1,3,3,1,3,9,9,6,12,18,15,21,37,36,33,55,69,66,90,117,111,136,195,204,
%T A261633 217,294,330,342,447,531,541,657,804,839,978,1215,1288,1419,1755,1936,
%U A261633 2094,2535,2846,3027,3588,4123,4392,5073,5869,6261,7080
%N A261633 Expansion of Product_{k>=0} (1+x^(3*k+1))^3.
%F A261633 a(n) ~ exp(Pi*sqrt(n/3)) / (2 * 3^(1/4) * n^(3/4)).
%t A261633 nmax=50; CoefficientList[Series[Product[(1+x^(3*k+1))^3, {k, 0, nmax}], {x, 0, nmax}], x]
%Y A261633 Cf. A261612, A261615, A261634.
%K A261633 nonn
%O A261633 0,2
%A A261633 _Vaclav Kotesovec_, Aug 27 2015