A009068 Expansion of e.g.f. cos(tan(tan(x))), even terms only.

1, -1, -15, -513, -31007, -2881089, -376412847, -64825974593, -13951231536191, -3556538162237313, -998391201911168335, -261420586488162589057, -14787500346745601332575, 86170769393986400590463039

Offset

0,3

Links

G. C. Greubel, Table of n, a(n) for n = 0..223

Mathematica

With[{nmax = 60}, CoefficientList[Series[Cos[Tan[Tan[x]]], {x, 0, nmax}], x]*Range[0, nmax]!][[1 ;; -1 ;; 2]] (* G. C. Greubel, Jul 24 2018 *)

Prog

(PARI) x='x+O('x^60); v=Vec(serlaplace(cos(tan(tan(x))))); vector(#v\2, n, v[2*n-1]) \\ G. C. Greubel, Jul 24 2018

Crossrefs

Sequence in context: A218632 A218235 A212739 * A268960 A157166 A074040

Adjacent sequences: A009065 A009066 A009067 * A009069 A009070 A009071

Keyword

sign

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Status

approved