A013040 arctanh(sinh(x)+arcsin(x))=2*x+18/3!*x^3+938/5!*x^5+122066/7!*x^7...

2, 18, 938, 122066, 29635154, 11561687346, 6615385296570, 5218960553242866, 5429404407724397474, 7201623832416658882514, 11862352305394237757311946, 23755795427038939521773734290

Offset

0,1

Links

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

Formula

a(n) ~ (2*n)! / r^(2*n+1), where r = 0.4803099786153606144946517326733725892405... is the root of the equation sinh(r)+arcsin(r) = 1. - Vaclav Kotesovec, Feb 05 2015

Mathematica

nn = 20; Table[(CoefficientList[Series[ArcTanh[ArcSin[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: A180606 A334553 A369677 * A268051 A268074 A202544

Adjacent sequences: A013037 A013038 A013039 * A013041 A013042 A013043

Keyword

nonn

Author

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

Status

approved