A009711 Expansion of e.g.f.: tan(tanh(log(1+x))).

0, 1, -1, 2, -6, 16, 0, -568, 7504, -78248, 739080, -6314848, 44072688, -125928464, -3754236304, 114500663552, -2264653307520, 37495468333696, -536284797406848, 6159440282136320, -34551694794080000, -931439976890484224

Offset

0,4

Links

Table of n, a(n) for n=0..21.

Mathematica

With[{nn=30}, CoefficientList[Series[Tan[Tanh[Log[1+x]]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Aug 30 2020 *)

Crossrefs

Sequence in context: A181993 A123475 A193341 * A009586 A009487 A009806

Adjacent sequences: A009708 A009709 A009710 * A009712 A009713 A009714

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Definition clarified and previous Mathematica program replaced by Harvey P. Dale, Aug 30 2020

Status

approved