|
%I #9 Nov 28 2016 20:55:58
%S 2,16,808,98432,22498432,8253398272,4441967893504,3295980115392512,
%T 3225082749950656512,4023514822062532460544,6233513843421340514123776,
%U 11741363464465799639674126336
%N arctanh(arctan(x)+tan(x))=2*x+16/3!*x^3+808/5!*x^5+98432/7!*x^7...
%F a(n) ~ (2*n)! / r^(2*n+1), where r = 0.4952542103931914966377065988697787139312... is the root of the equation arctan(r)+tan(r) = 1. - _Vaclav Kotesovec_, Feb 05 2015
%t nn = 20; Table[(CoefficientList[Series[ArcTanh[ArcTan[x] + Tan[x]], {x, 0, 2*nn+1}], x] * Range[0, 2*nn+1]!)[[n]], {n, 2, 2*nn, 2}] (* _Vaclav Kotesovec_, Feb 05 2015 *)
%K nonn
%O 0,1
%A Patrick Demichel (patrick.demichel(AT)hp.com)
|
