A009715 Expansion of tan(tanh(x))*cos(x).

1, -3, -3, 273, -5159, -62139, 16414101, -1357293927, 59192332081, 5204089208589, -1943937262679379, 331586038355507361, -32236263434125968887, -1484274347735103183531, 1139055571050751311941445

Offset

0,2

Links

Table of n, a(n) for n=0..14.

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Tan[Tanh[x]]*Cos[x], {x, 0, nn}], x] Range[0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, Jan 23 2026 *)

Crossrefs

Sequence in context: A113457 A113466 A007301 * A344283 A335258 A292163

Adjacent sequences: A009712 A009713 A009714 * A009716 A009717 A009718

Keyword

sign

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Previous Mathematica program replaced by Harvey P. Dale, Jan 23 2026

Status

approved