A013296 tan(arctanh(x)-log(x+1)) = 1/2!*x^2 + 6/4!*x^4 + 150/6!*x^6 + 7560/8!*x^8...

0, 1, 6, 150, 7560, 642600, 82328400, 14799985200, 3550699152000, 1095489931536000, 422416533258720000, 199001229578030880000, 112442434205652270720000, 75042084306026165328000000

Offset

0,3

Links

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

Formula

a(n) ~ 2 * (2*n)! * exp(Pi*n) / (exp(Pi)-1)^(n+1). - Vaclav Kotesovec, Feb 06 2015

Mathematica

nn = 20; Table[(CoefficientList[Series[Tan[ArcTanh[x] - Log[1 + x]], {x, 0, 2*nn}], x] * Range[0, 2*nn]!)[[n]], {n, 1, 2*nn+1, 2}] (* Vaclav Kotesovec, Feb 06 2015 *)

Crossrefs

Sequence in context: A065946 A222051 A285747 * A013301 A233734 A227044

Adjacent sequences: A013293 A013294 A013295 * A013297 A013298 A013299

Keyword

nonn

Author

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

Extensions

a(0)=0 prepended by Vaclav Kotesovec, Feb 06 2015

Definition modified by Vaclav Kotesovec, Feb 06 2015

Status

approved