A009104 - OEIS

A009104

Expansion of e.g.f. cos(x)/cos(sin(x)), even powers only.

1, 0, -4, -24, 272, 14528, 181312, -20265088, -1771263744, -4388386816, 16325400792064, 1796402984175616, -109123852786069504, -68488660591133114368, -7567377513364063567872

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,3

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..250

MATHEMATICA

With[{nmax = 60}, CoefficientList[Series[Cos[x]/Cos[Sin[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(sin(x)))); vector(#v\2, n, v[2*n-1]) \\ G. C. Greubel, Jul 26 2018

CROSSREFS

Sequence in context: A077700 A080489 A101228 * A255440 A052727 A219118

Adjacent sequences: A009101 A009102 A009103 * A009105 A009106 A009107

KEYWORD

sign

AUTHOR

R. H. Hardin

EXTENSIONS

Extended with signs by Olivier Gérard, Mar 15 1997

STATUS

approved