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 A012003 #13 Nov 21 2013 12:46:00
%S A012003 1,0,-3,-30,-483,-12660,-492063,-26407290,-1854592743,-162954226920,
%T A012003 -17150991170523,-2051454240374550,-254425037609483403,
%U A012003 -24186909676571913180,3098088521295623020617
%N A012003 E.g.f. cos(log(cos(x))), even powers only.
%F A012003 For n>1, a(n) appears to be divisible by 3, and the highest exponent of 2 in a(2m+1) seems to be A001511(m). - _Ralf Stephan_, Aug 14 2013
%t A012003 With[{nn=30},Take[CoefficientList[Series[Cos[Log[Cos[x]]],{x,0,nn}],x] Range[0,nn]!,{1,-1,2}]] (* _Harvey P. Dale_, Aug 29 2011 *)
%K A012003 sign
%O A012003 0,3
%A A012003 Patrick Demichel (patrick.demichel(AT)hp.com)