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%I #6 Aug 07 2017 12:37:15
%S 1,-1,17,-449,30113,-2761793,415351089,-81370683393,21955730621249,
%T -7408485122203009,3161408870916725841,-1630838373598845388097,
%U 1013685573603673847917793,-741353146138643571687256001
%N arcsinh(arcsin(arcsinh(x)))=x-1/3!*x^3+17/5!*x^5-449/7!*x^7+30113/9!*x^9...
%t With[{nn=30},Take[CoefficientList[Series[ArcSinh[ArcSin[ArcSinh[x]]],{x,0,nn}],x] Range[0,nn-1]!,{2,-1,2}]] (* _Harvey P. Dale_, Aug 07 2017 *)
%K sign
%O 0,3
%A Patrick Demichel (patrick.demichel(AT)hp.com)