OFFSET
0,8
FORMULA
a(n) = Sum_{k=0..floor(n/3)} binomial(k,n-3*k)^2.
PROG
(PARI) my(N=50, x='x+O('x^N)); Vec(1/sqrt((1-x^3-x^4)^2-4*x^7))
(PARI) a(n) = sum(k=0, n\3, binomial(k, n-3*k)^2);
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Oct 02 2024
STATUS
approved