OFFSET
0,4
LINKS
Index entries for linear recurrences with constant coefficients, signature (1,0,3,0,3,0,1).
FORMULA
a(n) = a(n-1) + 3*a(n-3) + 3*a(n-5) + a(n-7).
a(n) = Sum_{k=0..floor(3*n/7)} binomial(3*n-6*k,k).
PROG
(PARI) a(n) = sum(k=0, 3*n\7, binomial(3*n-6*k, k));
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Seiichi Manyama, Jun 15 2024
STATUS
approved