A012003 E.g.f. cos(log(cos(x))), even powers only.

1, 0, -3, -30, -483, -12660, -492063, -26407290, -1854592743, -162954226920, -17150991170523, -2051454240374550, -254425037609483403, -24186909676571913180, 3098088521295623020617

Offset: 0

Author

Patrick Demichel (patrick.demichel(AT)hp.com)

Keywords

• sign

Programs

Mathematica

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 *)

Formula

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