%I #6 Dec 27 2013 13:50:20
%S 1,2,48,1080,112000,9941120,2204340864,473940603136,177280211177472,
%T 70742192264802304,40258836839175946240,25560794070720075464704,
%U 20755313571874776988942336,19066653840381485832858304512
%N arcsin(sec(x)*arctan(x))=x+2/3!*x^3+48/5!*x^5+1080/7!*x^7+112000/9!*x^9...
%t With[{nn=30},Take[CoefficientList[Series[ArcSin[Sec[x]ArcTan[x]],{x,0,nn}],x] Range[0,nn-1]!,{2,-1,2}]] (* _Harvey P. Dale_, Dec 27 2013 *)
%K nonn
%O 0,2
%A Patrick Demichel (patrick.demichel(AT)hp.com)