A009091 - OEIS

A009091

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

1, -1, 21, -597, 26537, -1834249, 180938109, -23781199197, 3989919982673, -830092069266577, 209479116176732901, -62986349633232396261, 22231865269167169440761, -9096170536950779556167833

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OFFSET

0,3

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..238

MAPLE

seq(coeff(series(factorial(n)*cos(tanh(x)*cos(x)), x, n+1), x, n), n=0..30, 2); # Muniru A Asiru, Jul 26 2018

MATHEMATICA

With[{nmax = 60}, CoefficientList[Series[Cos[Tanh[x]*Cos[x]], {x, 0, nmax}], x]*Range[0, nmax]!][[1 ;; -1 ;; 2]] (* G. C. Greubel, Jul 25 2018 *)

PROG

(PARI) x='x+O('x^50); v=Vec(serlaplace(cos(tanh(x)*cos(x)))); vector(#v\2, n, v[2*n-1]) \\ G. C. Greubel, Jul 25 2018

CROSSREFS

Sequence in context: A089457 A265631 A352433 * A231639 A159278 A296672

Adjacent sequences: A009088 A009089 A009090 * A009092 A009093 A009094

KEYWORD

sign

AUTHOR

R. H. Hardin

EXTENSIONS

Extended with signs by Olivier Gérard, Mar 15 1997

STATUS

approved