A009717 Expansion of e.g.f. tan(tanh(x))*sin(x) (even powers only).

0, 2, -4, -42, 1336, -16726, -1194700, 153304830, -10698400400, 188012481362, 107922523124588, -26275693823306202, 3726087789656495272, -203071274271083537926, -64313415452872137435484

Offset

0,2

Links

Robert Israel, Table of n, a(n) for n = 0..243

Maple

S:= series(tan(tanh(x))*sin(x), x, 51):
seq(coeff(S, x, i)*i!, i=0..50, 2); # Robert Israel, Mar 10 2025

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Tan[Tanh[x]]*Sin[x], {x, 0, nn}], x] Range[ 0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Jun 14 2019 *)

Crossrefs

Sequence in context: A009811 A364237 A009591 * A018317 A359876 A059794

Adjacent sequences: A009714 A009715 A009716 * A009718 A009719 A009720

Keyword

sign,changed

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Prior Mathematica program replaced by Harvey P. Dale, Jun 14 2019

Name clarified by Robert Israel, Mar 10 2025

Status

approved