A009758 Expansion of e.g.f. tan(x)/cos(tanh(x)) (odd powers only).

1, 5, 21, 377, 17161, 442925, 38819613, 3394928609, 307139569297, 50204583973973, 8330000263573413, 1585633516380134729, 416021432525199858841, 118441213090527475221629, 35638847609472720069131181, 15336745055032862739772925873

Offset

1,2

Links

G. C. Greubel, Table of n, a(n) for n = 1..242

Mathematica

With[{nn=40}, Take[CoefficientList[Series[Tan[x]/Cos[Tanh[x]], {x, 0, nn}], x]*Range[0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, Dec 08 2012 *)

Prog

(PARI) x='x+O('x^50); v=Vec(serlaplace(tan(x)/cos(tanh(x)))); vector((#v-1)\2 , n, v[2*n-1]) \\ G. C. Greubel, Feb 12 2018

Crossrefs

Sequence in context: A101694 A006109 A009732 * A143503 A144779 A193324

Adjacent sequences: A009755 A009756 A009757 * A009759 A009760 A009761

Keyword

nonn

Author

R. H. Hardin

Extensions

Extended and signs tested by Olivier Gérard, Mar 15 1997

More terms from Harvey P. Dale, Dec 08 2012

Status

approved