A009839 Expansion of e.g.f.: tanh(x)/cos(log(1+x)).

0, 1, 0, 1, -12, 76, -480, 4264, -45248, 514180, -6418080, 89205348, -1356339600, 22268993280, -393425899776, 7452539807088, -150601672807680, 3232773233449104, -73469416841374464, 1762493272462111632

Offset

0,5

Links

Harvey P. Dale, Table of n, a(n) for n = 0..150

Formula

a(n) ~ n! * (-1)^(n+1) * tanh(1-exp(-Pi/2)) / ((exp(Pi/2)-1) * (1-exp(-Pi/2))^n). - Vaclav Kotesovec, Jan 24 2015

Mathematica

With[{nn=20}, CoefficientList[Series[Tanh[x]/Cos[Log[1+x]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Aug 07 2013 *)

Crossrefs

Sequence in context: A044580 A075279 A009405 * A190066 A335253 A071767

Adjacent sequences: A009836 A009837 A009838 * A009840 A009841 A009842

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Definition clarified and prior Mathematica program replaced by Harvey P. Dale, Aug 07 2013

Status

approved