%I #6 Mar 21 2015 16:43:46
%S 1,1,17,721,56545,7062241,1283497841,319471153457,104260273696961,
%T 43168502192389825,22100367268731836881,13703484478282258062481,
%U 10117607255517016666964897,8769262856125733251376413601
%N cosh(tan(arctanh(x)))=1+1/2!*x^2+17/4!*x^4+721/6!*x^6+56545/8!*x^8...
%t With[{nn=30},Take[CoefficientList[Series[Cosh[Tan[ArcTanh[x]]],{x,0,nn}],x] Range[0,nn]!,{1,-1,2}]] (* _Harvey P. Dale_, Mar 21 2015 *)
%K nonn
%O 0,3
%A Patrick Demichel (patrick.demichel(AT)hp.com)