A122509 Expansion of x/(1 - 2*x^2 - 21*x^3).

0, 1, 0, 2, 21, 4, 84, 449, 252, 2662, 9933, 10616, 75768, 229825, 374472, 2050778, 5575269, 11965468, 54216876, 141011585, 359708580, 1420577566, 3680660445, 10395035312, 37193449776, 98083939969, 292682641104, 977230325234

Offset

0,4

Links

G. C. Greubel, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (0,2,21).

Formula

G.f.: x/(1 - 2*x^2 - 21*x^3).

Mathematica

CoefficientList[Series[x/(1 -2*x^2 -21*x^3), {x, 0, 30}], x]

Prog

(Magma) I:=[0, 1, 0]; [n le 3 select I[n] else 2*Self(n-2) +21*Self(n-3): n in [1..31]]; // G. C. Greubel, Jul 11 2021
(Sage)
def A122509_list(prec):
    P.<x> = PowerSeriesRing(ZZ, prec)
    return P( x/(1 -2*x^2 -21*x^3) ).list()
A122509_list(30) # G. C. Greubel, Jul 11 2021

Crossrefs

Sequence in context: A377413 A100980 A360980 * A024230 A358520 A105666

Adjacent sequences: A122506 A122507 A122508 * A122510 A122511 A122512

Keyword

nonn,easy

Author

Roger L. Bagula, Sep 15 2006

Extensions

Edited by G. C. Greubel, Jul 11 2021

Status

approved