OFFSET
0,3
FORMULA
a(n) = (1/n) * Sum_{k=0..n} binomial(n,k) * binomial(n-4*k,n-k-1) for n > 0.
PROG
(PARI) a(n) = if(n==0, 1, sum(k=0, n, binomial(n, k)*binomial(n-4*k, n-k-1))/n);
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Apr 11 2024
STATUS
approved