A013064 arctanh(sinh(x)+arctan(x))=2*x+15/3!*x^3+713/5!*x^5+82481/7!*x^7...

2, 15, 713, 82481, 17926289, 6251997081, 3199183099305, 2256926363091921, 2099642392012962209, 2490468291041882743721, 3668423635534285779378041, 6569558349739213693016437665

Offset

0,1

Links

Table of n, a(n) for n=0..11.

Formula

a(n) ~ (2*n)! / r^(2*n+1), where r = 0.5079168569437311537765199369846945055215... is the root of the equation sinh(r)+arctan(r) = 1. - Vaclav Kotesovec, Feb 05 2015

Mathematica

nn = 20; Table[(CoefficientList[Series[ArcTanh[ArcTan[x] + Sinh[x]], {x, 0, 2*nn+1}], x] * Range[0, 2*nn+1]!)[[n]], {n, 2, 2*nn, 2}] (* Vaclav Kotesovec, Feb 05 2015 *)

Crossrefs

Sequence in context: A015185 A203467 A071627 * A013095 A208051 A038017

Adjacent sequences: A013061 A013062 A013063 * A013065 A013066 A013067

Keyword

nonn

Author

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

Status

approved