A012054 - OEIS

%I #8 Jan 23 2013 17:20:34

%S 1,-1,9,-225,3345,-893025,-36212775,-20892252225,-3614048241375,

%T -1664630362370625,-584598534985164375,-327627617091486830625,

%U -181787523574523506599375,-131875411531849225343390625

%N arctan(sin(arctanh(x)))=x-1/3!*x^3+9/5!*x^5-225/7!*x^7+3345/9!*x^9...

%t With[{nn=30},Take[CoefficientList[Series[ArcTan[Sin[ArcTanh[x]]],{x,0,nn}],x]Range[0,nn-1]!,{2,-1,2}]] (* _Harvey P. Dale_, Jan 23 2013 *)

%K sign

%O 0,3

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

%E Definition clarified by _Harvey P. Dale_, Jan 23 2013