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 A012036 #9 Feb 03 2015 05:07:56
%S A012036 1,0,-4,32,80,-34048,5048512,-984048128,246504417536,-76892124225536,
%T A012036 29350173573487616,-13506119868179701760,7388967312556159062016,
%U A012036 -4745632815309786449379328,3538391474251613805070172160
%N A012036 tan(sin(arcsinh(x)))=x-4/5!*x^5+32/7!*x^7+80/9!*x^9-34048/11!*x^11...
%H A012036 Vaclav Kotesovec, <a href="/A012036/b012036.txt">Table of n, a(n) for n = 0..200</a>
%F A012036 a(n) ~ (-1)^n * c * (2*n)! / sqrt(n), where c = 0.05565047582054219883411112937... . - _Vaclav Kotesovec_, Feb 03 2015
%t A012036 With[{nn=30},Take[CoefficientList[Series[Tan[Sin[ArcSinh[x]]],{x,0,nn}],x] Range[0,nn-1]!,{2,-1,2}]] (* _Harvey P. Dale_, May 19 2014 *)
%K A012036 sign
%O A012036 0,3
%A A012036 Patrick Demichel (patrick.demichel(AT)hp.com)