OFFSET
0,2
FORMULA
a(n) = (1/(n+1)) * Sum_{k=0..n} 16^k * binomial(n/4+1/4,k) * binomial(k,n-k).
a(4*n+3) = 0 for n >= 0.
a(n) = 16^n*binomial((n+1)/4, n)*hypergeom([(1-n)/2, -n/2], [(5-3*n)/4], 1/4)/(n+1). - Stefano Spezia, Apr 18 2024
PROG
(PARI) a(n) = sum(k=0, n, 16^k*binomial(n/4+1/4, k)*binomial(k, n-k))/(n+1);
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Apr 15 2024
STATUS
approved