OFFSET
0,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (3,0,-5,0,3,1).
FORMULA
MATHEMATICA
CoefficientList[Series[((1 + 2*x)/(1 - x - x^2))^3, {x, 0, 50}], x] (* or *) LinearRecurrence[{3, 0, -5, 0, 3, 1}, {1, 9, 39, 120, 315, 753}, 30] (* G. C. Greubel, Dec 21 2017 *)
PROG
(PARI) x='x+O('x^30); Vec(((1+2*x)/(1-x-x^2))^3) \\ G. C. Greubel, Dec 21 2017
(Magma) I:=[1, 9, 39, 120, 315, 753]; [n le 6 select I[n] else 3*Self(n-1) - 5*Self(n-3) + 3*Self(n-5) + Self(n-6): n in [1..30]]; // G. C. Greubel, Dec 21 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Apr 20 2001
STATUS
approved