A013336 Expansion of e.g.f.: arctanh(exp(x)-sec(x)).

0, 1, 0, 3, -4, 45, -180, 1743, -13704, 135705, -1613160, 18065883, -276222604, 3655783365, -65652672540, 1034667581223, -20865280018704, 387014665823025, -8593188683674320, 184059142857923763, -4464138375366282004, 108277288526211374685, -2858191345505462554500

Offset

0,4

Links

Table of n, a(n) for n=0..22.

Example

x + (3/3!)*x^3 - (4/4!)*x^4 + (45/5!)*x^5 - (180/6!)*x^6 + (1743/7!)*x^7 - ...

Mathematica

With[{nn=20}, CoefficientList[Series[ArcTanh[Exp[x]-Sec[x]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Oct 11 2014 *)

Crossrefs

Sequence in context: A041055 A246626 A032838 * A264509 A198051 A032839

Adjacent sequences: A013333 A013334 A013335 * A013337 A013338 A013339

Keyword

sign

Author

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

Extensions

Definition clarified and zero prepended by Harvey P. Dale, Oct 11 2014

Name edited by Michel Marcus, Sep 01 2019

More terms from Petros Hadjicostas, Sep 01 2019

Status

approved