%I #8 Feb 05 2015 15:44:54
%S 2,17,865,109007,25619185,9676271447,5360201676505,4094035686738287,
%T 4123461735603625825,5295201587012317791527,8444330016251458512555145,
%U 16372171162004294836053543167
%N E.g.f.: arctanh(tan(x)+sin(x))=2*x+17/3!*x^3+865/5!*x^5+109007/7!*x^7...
%F a(n) ~ (2*n)! / (arctan((1-sqrt(2) + sqrt(2*sqrt(2)-1)) / (sqrt(2)-1 + sqrt(2*sqrt(2)-1))))^(2*n+1). - _Vaclav Kotesovec_, Feb 05 2015
%t With[{nn=30},Take[CoefficientList[Series[ArcTanh[Tan[x]+Sin[x]],{x,0,nn}],x]Range[0,nn-1]!,{2,-1,2}]] (* _Harvey P. Dale_, Jun 26 2012 *)
%K nonn
%O 0,1
%A Patrick Demichel (patrick.demichel(AT)hp.com)
%E Definition clarified by _Harvey P. Dale_, Jun 26 2012