Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.
%I #6 Nov 28 2016 17:57:52
%S 1,-1,17,-617,44417,-5210129,909126033,-220910314809,71341157623169,
%T -29556627270426145,15282372258542389905,-9645984260739983339273,
%U 7298836347461102485422593,-6521512480584315170326457393
%N arctanh(arctan(arcsinh(x)))=x-1/3!*x^3+17/5!*x^5-617/7!*x^7+44417/9!*x^9...
%t With[{nn=30},Take[CoefficientList[Series[ArcTanh[ArcTan[ArcSinh[x]]],{x,0,nn}],x] Range[0,nn-1]!,{2,-1,2}]] (* _Ray Chandler_, Nov 28 2016 *)
%K sign
%O 0,3
%A Patrick Demichel (patrick.demichel(AT)hp.com)