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
KEYWORD
nonn,easy
AUTHOR
Roger L. Bagula, Sep 15 2006
EXTENSIONS
Edited by G. C. Greubel, Jul 11 2021
STATUS
approved