A012844 - OEIS

%I #6 Sep 18 2013 11:19:36

%S 1,3,-7,-917,-7183,3803987,316369129,-40892465221,-12655402122271,

%T 1539257113273507,1652188971379360217,198029913991075323147,

%U -231213557728594141960239,-76270663840340687485107213

%N arctan(sec(x)*arctanh(x))=x+3/3!*x^3-7/5!*x^5-917/7!*x^7-7183/9!*x^9...

%t With[{nn=30},Take[CoefficientList[Series[ArcTan[Sec[x]ArcTanh[x]],{x,0,nn}],x] Range[0,nn-1]!,{2,-1,2}]] (* _Harvey P. Dale_, Sep 18 2013 *)

%K sign

%O 0,2

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

%E Definition clarified by _Harvey P. Dale_, Sep 18 2013