OFFSET
0,2
COMMENTS
a(100) is negative.
FORMULA
a(n) = Sum_{k=0..n} 4^(n-k) * binomial(k+2,2) * binomial(3*k/2,n-k).
PROG
(PARI) a(n) = sum(k=0, n, 4^(n-k)*binomial(k+2, 2)*binomial(3*k/2, n-k));
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Seiichi Manyama, Apr 02 2025
STATUS
approved
