A013099 - OEIS

%I #9 Oct 24 2013 16:23:32

%S 2,17,873,110127,25968897,9837102007,5465752395569,4187179894797967,

%T 4229947817463760257,5448264281798198909031,8714522311726067909334321,

%U 16946786732387040593899895551

%N arctanh(arcsinh(x)+tan(x)) = 2*x+17/3!*x^3+873/5!*x^5+110127/7!*x^7...

%F a(n) ~ (2*n)! / r^(2*n+1), where r = 0.48741523182648... is the root of the equation log(sqrt(r^2+1)-r) = tan(r)-1. - _Vaclav Kotesovec_, Oct 24 2013

%t Table[n!*SeriesCoefficient[ArcTanh[ArcSinh[x]+Tan[x]],{x,0,n}],{n,1,41,2}] (* _Vaclav Kotesovec_, Oct 24 2013 *)

%K nonn

%O 0,1

%A Patrick Demichel (patrick.demichel(AT)hp.com)