%I #8 Mar 02 2015 17:41:09

%S 1,1,1,49,1345,105441,10336833,1580651409,316289380737,83559601907649,

%T 27709107620492673,11345006679686949105,5605389007592066373825,

%U 3292126822668986935347105,2265914784466771293436282305,1806802766658673683522189272145

%N cosh(arctan(arctanh(x)))=1+1/2!*x^2+1/4!*x^4+49/6!*x^6+1345/8!*x^8...

%t With[{nn=30},Take[CoefficientList[Series[Cosh[ArcTan[ArcTanh[x]]],{x,0,nn}],x] Range[0,nn]!,{1,-1,2}]] (* _Harvey P. Dale_, Mar 02 2015 *)

%K nonn

%O 0,4

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

%E More terms from _Harvey P. Dale_, Mar 02 2015