%I #9 May 28 2017 09:08:01
%S 1,10,280,15440,1412480,193606400,37162777600,9519986944000,
%T 3139364220928000,1295834618224640000,654668849830461440000,
%U 397456058751397068800000,285567610965661253632000000
%N -log(cos(arctanh(x)))=1/2!*x^2+10/4!*x^4+280/6!*x^6+15440/8!*x^8...
%t With[{nn=30},Take[CoefficientList[Series[-Log[Cos[ArcTanh[x]]],{x,0,nn}],x] Range[0,nn]!,{3,-1,2}]] (* _Harvey P. Dale_, May 28 2017 *)
%K nonn
%O 0,2
%A Patrick Demichel (patrick.demichel(AT)hp.com)
%E Edited by _D. S. McNeil_, Dec 17 2011