A009809 Expansion of tanh(tan(x))*cos(x).

1, -3, -3, 49, 2905, 83589, -334059, -351159815, -39776495567, -2339943411315, 181395497796525, 87834301596283969, 15443686178950893193, 532878946672338704661, -705534269899082168140347

Offset

0,2

Links

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

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Tanh[Tan[x]]*Cos[x] , {x, 0, nn}], x] Range[ 0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, Jan 15 2023 *)

Crossrefs

Sequence in context: A083391 A165636 A142469 * A265717 A292753 A268136

Adjacent sequences: A009806 A009807 A009808 * A009810 A009811 A009812

Keyword

sign

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Prior Mathematica program removed by Harvey P. Dale, Jan 15 2023

Status

approved