%I #6 Nov 28 2016 20:40:53
%S 2,448,2380032,69695846400,6697099792220160,1606188416621920911360,
%T 810882197441673837894696960,766865924510666637669136261447680
%N arctanh(arctanh(x)*arctan(x))=2/2!*x^2+448/6!*x^6+2380032/10!*x^10...
%t With[{nn=30},Take[CoefficientList[Series[ArcTanh[ArcTanh[x]*ArcTan[x]],{x,0,nn}],x] Range[0,nn]!,{3,-1,4}]] (* _Ray Chandler_, Nov 28 2016 *)
%K nonn
%O 0,1
%A Patrick Demichel (patrick.demichel(AT)hp.com)