OFFSET
0,6
FORMULA
a(4*n) = 9^(n-1) for n > 0.
a(n) = Sum_{k=0..floor(n/4)} 8^k * binomial(n/4-1,k).
PROG
(PARI) a(n) = sum(k=0, n\4, 8^k*binomial(n/4-1, k));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jun 07 2024
STATUS
approved