A024229 Expansion of e.g.f.: tanh(x)*sin(tan(x))/2 (even part).

0, 1, -2, 19, -1572, -24763, -5174758, -230357353, -45947071688, -3138700558071, -787255563055690, -40961532387015781, -13644908739614623724, 5015831039379054245197, 1910018990150165668013778, 1856616739480127236630886175, 892801482776535024911075390576

Offset

0,3

Links

Stefano Spezia, Table of n, a(n) for n = 0..200

Mathematica

nmax=200; expan=Series[Tanh[x]*Sin[Tan[x]]/2, {x, 0, 2*nmax}]; Join[{0}, Table[(2n)! Coefficient[expan, x^(2n)], {n, nmax}]] (* Stefano Spezia, Sep 17 2022 *)

Prog

(PARI) my(x='x+O('x^50), v=Vec(serlaplace(tanh(x)*sin(tan(x))/2))); concat(0, vector(#v\2, k, v[2*k-1])) \\ Michel Marcus, Sep 17 2022

Crossrefs

Cf. A009834.

Sequence in context: A350933 A172028 A365050 * A094663 A274762 A091688

Adjacent sequences: A024226 A024227 A024228 * A024230 A024231 A024232

Keyword

sign

Author

R. H. Hardin

Extensions

Extended with signs, Mar 1997

Status

approved