%I #11 Nov 29 2016 08:31:27
%S 2,13,561,58959,11644353,3689490231,1715357184849,1099472915829519,
%T 929329108531548417,1001522171480774224743,1340339793936610136490513,
%U 2180857643900986608848041983,4239717441519601414508854360257
%N arctanh(arcsinh(x)+arctan(x))=2*x+13/3!*x^3+561/5!*x^5+58959/7!*x^7...
%F a(n) ~ (2*n)! / r^(2*n+1), where r = 0.53286199991370386509144685314983925384646... is the root of the equation arcsinh(r)+arctan(r) = 1. - _Vaclav Kotesovec_, Feb 05 2015
%t With[{nn=30},Take[CoefficientList[Series[ArcTanh[ArcSinh[x]+ArcTan[x]], {x,0,nn}],x]Range[0,nn-1]!,{2,-1,2}]] (* _Harvey P. Dale_, Nov 02 2011 *)
%K nonn
%O 0,1
%A Patrick Demichel (patrick.demichel(AT)hp.com)