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 A012461 #8 Nov 28 2016 18:50:11
%S A012461 0,2,-16,488,-30336,3061152,-450481920,90676698240,-23889578496000,
%T A012461 7972943138664960,-3286129765438771200,1638857583672607549440,
%U A012461 -972524875970827007262720,677113960144029088030433280
%N A012461 sinh(arctan(x)*arctan(x))=2/2!*x^2-16/4!*x^4+488/6!*x^6-30336/8!*x^8...
%t A012461 nn = 20; Table[(CoefficientList[Series[Sinh[ArcTan[x]^2], {x, 0, 2*nn}], x] * Range[0, 2*nn]!)[[n]], {n, 1, 2*nn+1, 2}] (* _Vaclav Kotesovec_, Feb 08 2015 *)
%K A012461 sign
%O A012461 0,2
%A A012461 Patrick Demichel (patrick.demichel(AT)hp.com)
%E A012461 a(0)=0 prepended by _Vaclav Kotesovec_, Feb 08 2015