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A366677
G.f. satisfies A(x) = 1 + x^4 + x*A(x)^4.
1
1, 1, 4, 22, 141, 973, 7112, 54040, 422552, 3377770, 27478568, 226753828, 1893462584, 15969598554, 135842638632, 1164075017512, 10039732285528, 87081507756245, 759128176746864, 6647475055207618, 58445784269830824, 515745587816906733
OFFSET
0,3
FORMULA
a(n) = Sum_{k=0..floor(n/4)} binomial(3*(n-4*k)+1,k) * binomial(4*(n-4*k),n-4*k)/(3*(n-4*k)+1).
PROG
(PARI) a(n) = sum(k=0, n\4, binomial(3*(n-4*k)+1, k)*binomial(4*(n-4*k), n-4*k)/(3*(n-4*k)+1));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Oct 16 2023
STATUS
approved