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 A291583 #15 Aug 31 2017 02:55:06
%S A291583 1,2,4,8,18,36,72,144,292,586,1172,2344,4696,9396,18792,37584,75186,
%T A291583 150380,300764,601528,1203092,2406200,4812408,9624816,19249704,
%U A291583 38499446,76998908,153997824,307995792,615991660,1231983352,2463966720,4927933732,9855867616
%N A291583 Expansion of Product_{k>=1} 1/(1 - 2*x^(k^2)).
%F A291583 a(n) = c * 2^n, where c = Product_{k>=2} 1/(1 - 2^(1-k^2)) = 1.1473740190706250791012378892728990358979800885299281286906257674366893358222...
%t A291583 nmax = 30; CoefficientList[Series[Product[1/(1 - 2*x^(k^2)), {k, 1, nmax}], {x, 0, nmax}], x]
%Y A291583 Cf. A001156, A070933.
%K A291583 nonn
%O A291583 0,2
%A A291583 _Vaclav Kotesovec_, Aug 31 2017