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 A024263 #11 Jan 20 2015 12:52:32
%S A024263 0,1,4,108,4448,276560,24034752,2782112704,413640580096,
%T A024263 76768625740032,17380983003345920,4711153236657376256,
%U A024263 1505098422997799215104,559357234754573189828608
%N A024263 Expansion of sinh(tan(x)*x)/2.
%C A024263 Limit n->infinity A024263(n)/A009252(n) = 1/4. - _Vaclav Kotesovec_, Jan 20 2015
%H A024263 Vaclav Kotesovec, <a href="/A024263/b024263.txt">Table of n, a(n) for n = 0..238</a>
%F A024263 a(n) ~ n^(2*n-1/4) * 2^(4*n-7/4) * exp(2*sqrt(2*n)-2*n-1/2) / Pi^(2*n) * (1 - (Pi^2-1)/(12*sqrt(2*n))). - _Vaclav Kotesovec_, Jan 20 2015
%t A024263 Sinh[ Tan[ x ]*x ]/2 (* Even Part *)
%t A024263 With[{nn=40}, Take[CoefficientList[Series[Sinh[Tan[x]*x]/2, {x, 0, nn}], x] * Range[0, nn]!, {1, -1, 2}]] (* _Vaclav Kotesovec_, Jan 20 2015 *)
%Y A024263 Cf. A009252, A009611.
%K A024263 nonn
%O A024263 0,3
%A A024263 _R. H. Hardin_
%E A024263 Extended and signs tested 03/97.