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 A012134 #7 Nov 21 2013 12:46:01
%S A012134 1,1,1,4,13,84,469,4208,33433,386064,3984681,56523072,718210725,
%T A012134 12121690944,183013440765,3589856932608,62801454477105,
%U A012134 1406019035808000,27970921286867025,704535958463063040
%N A012134 exp(arcsin(arctanh(x)))=1+x+1/2!*x^2+4/3!*x^3+13/4!*x^4+84/5!*x^5...
%t A012134 With[{nn=20},CoefficientList[Series[Exp[ArcSin[ArcTanh[x]]],{x,0,nn}], x] Range[0,nn]!] (* _Harvey P. Dale_, Oct 08 2011 *)
%K A012134 nonn
%O A012134 0,4
%A A012134 Patrick Demichel (patrick.demichel(AT)hp.com)