A012130 arctanh(arcsin(tanh(x)))=x+1/3!*x^3+9/5!*x^5+169/7!*x^7+6513/9!*x^9...

1, 1, 9, 169, 6513, 382449, 33949369, 4083320409, 654225568353, 132856897394785, 33620948951783145, 10322993203249787529, 3791611637554126839505, 1638719968206448148183889

Offset

0,3

Links

Table of n, a(n) for n=0..13.

Formula

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

Mathematica

nn = 20; Table[(CoefficientList[Series[ArcTanh[ArcSin[Tanh[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: A052774 A276960 A122725 * A151997 A119032 A215554

Adjacent sequences: A012127 A012128 A012129 * A012131 A012132 A012133

Keyword

nonn

Author

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

Status

approved