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A009095 Expansion of e.g.f. cos(tanh(x)/cos(x)), even powers only. 1
1, -1, -3, -117, -903, -111529, 687093, -320199453, 44530596081, -254346923089, 2006766293627373, 141849542553657147, 144420752722329270633, 17706925736601628695047, 16789499049770600380859877 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
LINKS
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 26 2018 *)
PROG
(PARI) x='x+O('x^60); v=Vec(serlaplace(cos(tanh(x)/cos(x)))); vector(#v\2, n, v[2*n-1]) \\ G. C. Greubel, Jul 26 2018
CROSSREFS
Sequence in context: A267897 A132304 A097642 * A326995 A155209 A037117
KEYWORD
sign
AUTHOR
EXTENSIONS
Extended with signs by Olivier Gérard, Mar 15 1997
STATUS
approved

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Last modified March 4 23:31 EST 2024. Contains 370537 sequences. (Running on oeis4.)