A012107 arctanh(arcsin(sinh(x)))=x+4/3!*x^3+84/5!*x^5+4432/7!*x^7+432144/9!*x^9...

1, 4, 84, 4432, 432144, 67336512, 15330202432, 4799825862912, 1978228668612864, 1038257514383795200, 676117122084133770240, 534973800492211106598912, 505535479689176978173726720

Offset

0,2

Links

Table of n, a(n) for n=0..12.

Formula

a(n) ~ (2*n)! / (arcsinh(sin(1)))^(2*n+1). - Vaclav Kotesovec, Feb 05 2015

Mathematica

nn = 20; Table[(CoefficientList[Series[ArcTanh[ArcSin[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: A012139 A012037 A012025 * A012189 A012076 A173211

Adjacent sequences: A012104 A012105 A012106 * A012108 A012109 A012110

Keyword

nonn

Author

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

Status

approved