A009099 Expansion of e.g.f. cos(x)*cos(tan(x)), even powers only.

1, -2, 0, -8, 192, 20480, 1837696, 187743488, 22698672128, 3236847570944, 536307107184640, 101121059849109504, 21095686709291679744, 4655115962946721611776, 983762698552391462027264

Offset

0,2

Links

G. C. Greubel, Table of n, a(n) for n = 0..241

Mathematica

With[{nmax = 60}, CoefficientList[Series[Cos[x]*Cos[Tan[x]], {x, 0, nmax}], x]*Range[0, nmax]!][[1 ;; -1 ;; 2]] (* G. C. Greubel, Jul 26 2018 *)

Prog

(PARI) x='x+O('x^60); v=Vec(serlaplace(cos(x)*cos(tan(x)))); vector(#v\2, n, v[2*n-1]) \\ G. C. Greubel, Jul 26 2018

Crossrefs

Sequence in context: A033836 A185159 A326240 * A193247 A373697 A091041

Adjacent sequences: A009096 A009097 A009098 * A009100 A009101 A009102

Keyword

sign

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Status

approved