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 A012530 #14 Nov 03 2013 07:52:54
%S A012530 2,232,685472,11496925312,641870470410752,90115671250751137792,
%T A012530 26741121618547455928082432,14898765702188922919730883100672,
%U A012530 14301272675149517137926114108443328512,22156614594176569412220482693952524899581952
%N A012530 arctanh(sinh(x)*sin(x)) = 2/2!*x^2+232/6!*x^6+685472/10!*x^10...
%F A012530 a(n) ~ 2*(4*n+1)! / r^(4*n+2), where r = 1.00572817652562... is the root of the equation sinh(r)*sin(r) = 1. - _Vaclav Kotesovec_, Oct 24 2013
%t A012530 Table[n!*SeriesCoefficient[ArcTanh[Sinh[x]*Sin[x]],{x,0,n}],{n,2,40,4}] (* _Vaclav Kotesovec_, Nov 02 2013 *)
%Y A012530 Bisection of A009359. - _Olivier Gérard_, Jun 04 2012
%K A012530 nonn
%O A012530 0,1
%A A012530 Patrick Demichel (patrick.demichel(AT)hp.com)