%I #7 Nov 21 2013 12:46:00
%S 1,1,-3,21,-647,45161,-4655115,671831421,-131445679375,33601481453521,
%T -10874248371483155,4345212201159011301,-2101132542287329737623,
%U 1209250716473417141359161
%N sec(sin(arcsinh(x)))=1+1/2!*x^2-3/4!*x^4+21/6!*x^6-647/8!*x^8...
%t With[{nn=30},Take[CoefficientList[Series[Sec[Sin[ArcSinh[x]]],{x,0,nn}], x]Range[0,nn]!,{1,-1,2}]] (* _Harvey P. Dale_, Nov 28 2011 *)
%K sign
%O 0,3
%A Patrick Demichel (patrick.demichel(AT)hp.com)