A009720 Expansion of tan(tanh(x)*cos(x)).

1, -3, -43, 2009, 6313, -9872907, 760322045, 105243758801, -41122814903471, 1873399639193325, 3032918686052577317, -1060046322104258754871, -196239553045718536023047, 335369132729230015620066021

Offset

0,2

Links

Table of n, a(n) for n=0..13.

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, Mar 20 2020 *)

Crossrefs

Sequence in context: A386511 A317343 A307248 * A300873 A333329 A351579

Adjacent sequences: A009717 A009718 A009719 * A009721 A009722 A009723

Keyword

sign

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Previous Mathematica program replaced by Harvey P. Dale, Mar 20 2020

Status

approved