A009789 Expansion of e.g.f.: tanh(log(1+x)^2).

0, 0, 2, -6, 22, -100, 308, 1512, -51144, 869472, -12648528, 168624720, -2029008720, 19500193440, -52358834400, -4526884091520, 184448883292800, -5247799551052800, 128265498107293440, -2787299439278250240

Offset

0,3

Links

Table of n, a(n) for n=0..19.

Example

tanh(log(x+1)^2) = 2/2!*x^2-6/3!*x^3+22/4!*x^4-100/5!*x^5...

Mathematica

With[{nn=20}, CoefficientList[Series[Tanh[Log[1+x]^2], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Mar 05 2016 *)

Crossrefs

Sequence in context: A318974 A012269 A012272 * A012271 A012266 A009468

Adjacent sequences: A009786 A009787 A009788 * A009790 A009791 A009792

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Definition (Name) clarified by and prior Mathematica program replaced by Harvey P. Dale, Mar 05 2016

Status

approved