A009261 E.g.f.: Expansion of exp(tanh(tanh(x))).

1, 1, 1, -3, -15, 33, 513, -403, -31007, -41247, 2881089, 12404989, -376412847, -3175861439, 64825974593, 925805229229, -13951231536191, -320290449542079, 3556538162237313, 131747901365358205, -998391201911168335

Offset

0,4

Links

Table of n, a(n) for n=0..20.

Mathematica

With[{nn=30}, CoefficientList[Series[Exp[Tanh[Tanh[x]]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Apr 08 2013 *)

Crossrefs

Sequence in context: A211441 A086380 A324303 * A331249 A102790 A317182

Adjacent sequences: A009258 A009259 A009260 * A009262 A009263 A009264

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Definition clarified by Harvey P. Dale, Apr 08 2013

Status

approved