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 A298993 #16 Apr 18 2018 11:23:41
%S A298993 1,-2,-2,-36,54,-476,556,-6088,35878,-156844,444164,-1734648,11948604,
%T A298993 -35313048,156354328,-864527760,4733447686,-12692853452,54065039380,
%U A298993 -226098757912,1278838329812,-5257771138376,19455009120232,-76455773381360,453306681446748
%N A298993 Expansion of Product_{n>=1} 1/sqrt(1 + (4*x)^n).
%H A298993 Vaclav Kotesovec, <a href="/A298993/b298993.txt">Table of n, a(n) for n = 0..1000</a>
%F A298993 a(n) ~ (-1)^n * exp(Pi*sqrt(n/12)) * 4^(n-1) / (3^(1/4) * n^(3/4)). - _Vaclav Kotesovec_, Apr 18 2018
%t A298993 CoefficientList[Series[Sqrt[2/QPochhammer[-1, 4*x]], {x, 0, 20}], x] (* _Vaclav Kotesovec_, Apr 18 2018 *)
%Y A298993 Cf. A000984, A081362, A271235, A298994.
%K A298993 sign
%O A298993 0,2
%A A298993 _Seiichi Manyama_, Jan 31 2018