A009754 Expansion of e.g.f. tan(x)/cos(log(1+x)).

0, 1, 0, 5, -12, 116, -720, 7048, -67648, 789124, -9839520, 137625652, -2079277200, 34199202272, -604204537664, 11450703405872, -231315430836480, 4966162863717008, -112867805704455936, 2707812372195278800, -68377223974957136320, 1812971997782789669056

Offset

0,4

Links

G. C. Greubel, Table of n, a(n) for n = 0..430

Formula

a(n) ~ n! * (-1)^(n+1) * tan(1-exp(-Pi/2)) / ((exp(Pi/2)-1) * (1-exp(-Pi/2))^n). - Vaclav Kotesovec, Jan 24 2015

Mathematica

CoefficientList[Series[Sec[Log[1 + x]]*Tan[x], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 24 2015 *)

Prog

(PARI) x='x+O('x^30); concat([0], Vec(serlaplace(tan(x)/cos(log(1+x))))) \\ G. C. Greubel, Feb 12 2018

Crossrefs

Sequence in context: A009731 A009427 A267271 * A096314 A332466 A323565

Adjacent sequences: A009751 A009752 A009753 * A009755 A009756 A009757

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Status

approved