OFFSET
0,4
LINKS
Index entries for linear recurrences with constant coefficients, signature (1,3,0,-3,0,1).
FORMULA
G.f.: 1 / (1 - x/(1 - x^2)^3).
a(n) = a(n-1) + 3*a(n-2) - 3*a(n-4) + a(n-6) for n > 6.
PROG
(PARI) a(n) = sum(k=0, n\2, binomial(3*n-5*k-1, k));
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Seiichi Manyama, Jun 12 2024
STATUS
approved