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 A270663 #6 Mar 21 2016 06:41:13
%S A270663 1,-1,-11,-181,-9239,-148681,-49402979,6471717251,42662277841,
%T A270663 658656817939439,133531458273294661,168943525289665105979,
%U A270663 19015164932231993967289,62294481438650615377602599,18546969159687034895328945901,27398539855607539080934584895859
%N A270663 E.g.f.: Product_{k>=1} cos(x^k) [even terms only].
%H A270663 Vaclav Kotesovec, <a href="/A270663/b270663.txt">Table of n, a(n) for n = 0..224</a>
%t A270663 nmax = 20; Table[(Range[0, 2*nmax]! * CoefficientList[Series[Product[Cos[x^k], {k, 1, 2*nmax}], {x, 0, 2*nmax}], x])[[2*n + 1]], {n, 0, nmax}]
%Y A270663 Cf. A000262, A229263, A270294, A270662.
%K A270663 sign
%O A270663 0,3
%A A270663 _Vaclav Kotesovec_, Mar 21 2016