OFFSET
0,8
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (3,-3,1,0,0,-1).
FORMULA
G.f.: (1-x)^2/((1-x)^3 + x^6).
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) - a(n-6).
MATHEMATICA
LinearRecurrence[{3, -3, 1, 0, 0, -1}, {1, 1, 1, 1, 1, 1}, 45] (* Amiram Eldar, Oct 11 2021 *)
PROG
(PARI) a(n) = sum(k=0, n\6, (-1)^k*binomial(n-3*k, 3*k));
(PARI) my(N=66, x='x+O('x^N)); Vec((1-x)^2/((1-x)^3+x^6))
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Oct 11 2021
STATUS
approved