A009071 Expansion of e.g.f. cos(tan(x))*x, odd terms only.

1, -3, -35, -679, -18567, -587499, -9780459, 2502478065, 742659420913, 178572619407021, 44455465546363725, 12065488445289701385, 3615507259471920747625, 1195750896202918862106309, 433676146678880946251117189, 170620060022539628512713371809

Offset

0,2

Links

G. C. Greubel, Table of n, a(n) for n = 0..240

Formula

a(n) = (2*n+1)! * [x^(2*n+1)] cos(tan(x))*x. - Alois P. Heinz, Oct 01 2012

Mathematica

With[{nn=40}, Take[CoefficientList[Series[Cos[Tan[x]]*x, {x, 0, nn}], x] Range[0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, Oct 01 2012 *)

Prog

(PARI) x='x+O('x^50); v=Vec(serlaplace(x*cos(tan(x)))); vector((#v-1)\2 , n, v[2*n-1]) \\ G. C. Greubel, Jul 24 2018

Crossrefs

Sequence in context: A184554 A046032 A304191 * A093531 A129505 A185752

Adjacent sequences: A009068 A009069 A009070 * A009072 A009073 A009074

Keyword

sign

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

More terms from Harvey P. Dale, Oct 01 2012

Status

approved