%I #12 Nov 28 2016 18:32:17
%S 0,1,2,3,20,173,1190,11039,140968,1855481,26494858,441706331,
%T 8105309500,159190672613,3403623626286,78823813121975,
%U 1949180731782480,51354602068725361,1439864769232356882
%N arctanh(arctan(x)*exp(x))=x+2/2!*x^2+3/3!*x^3+20/4!*x^4+173/5!*x^5...
%F a(n) ~ (n-1)! / (2 * r^n), where r = 0.606555409757505028513842694060977136299... is the root of the equation arctan(r)*exp(r) = 1. - _Vaclav Kotesovec_, Feb 05 2015
%t With[{nn=25},CoefficientList[Series[ArcTanh[ArcTan[x]Exp[x]],{x,0,nn}], x]Range[0,nn]!] (* _Harvey P. Dale_, Oct 21 2011 *)
%K nonn
%O 0,3
%A Patrick Demichel (patrick.demichel(AT)hp.com)
%E Prepended missing a(0)=0 from _Vaclav Kotesovec_, Feb 05 2015
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