A009086 Expansion of e.g.f. cos(tanh(tan(x))), even powers only.

1, -1, 1, 47, 449, -18209, -1441087, -41192817, 2660018305, 460752070079, 21450325749889, -1057483104728337, 760394598152560705, 506532040802152000159, 99674104328764912612673

Offset

0,4

Links

G. C. Greubel, Table of n, a(n) for n = 0..242

Maple

seq(coeff(series(factorial(n)*cos(tanh(tan(x))), x, n+1), x, n), n=0..30, 2); # Muniru A Asiru, Jul 25 2018

Mathematica

With[{nmax = 60}, CoefficientList[Series[Cos[Tanh[Tan[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(tan(x))))); vector(#v\2, n, v[2*n-1]) \\ G. C. Greubel, Jul 25 2018

Crossrefs

Sequence in context: A126300 A012149 A106104 * A034779 A201090 A293368

Adjacent sequences: A009083 A009084 A009085 * A009087 A009088 A009089

Keyword

sign

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Status

approved