A009073 Expansion of e.g.f. cos(tan(x))/cosh(x), even terms only.

1, -2, 4, -128, 1296, -85600, 4372160, -148860416, 54261590272, 1474575037952, 1579094994228224, 145025202842173440, 87575771555229601792, 13290672132247757398016, 8077796113026531668901888

Offset

0,2

Links

G. C. Greubel, Table of n, a(n) for n = 0..240

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Cos[Tan[x]]/Cosh[x], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Feb 12 2015 *)

Prog

(PARI) x='x+O('x^50); v=Vec(serlaplace(cos(tan(x))/cosh(x))); vector(#v\2, n, v[2*n-1]) \\ G. C. Greubel, Jul 24 2018

Crossrefs

Sequence in context: A018493 A046035 A134710 * A326213 A369699 A012561

Adjacent sequences: A009070 A009071 A009072 * A009074 A009075 A009076

Keyword

sign

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Prior Mathematica program replaced by Harvey P. Dale, Feb 12 2015

Status

approved