A379159 G.f. A(x) satisfies A(x) = (1 + x^3) * (1 + x*A(x)^3).

1, 1, 3, 13, 59, 294, 1548, 8473, 47694, 274347, 1605553, 9529080, 57219636, 346989180, 2121996165, 13071868062, 81039237719, 505230120558, 3165528142389, 19922166970041, 125882558097870, 798300369383649, 5079196380442687, 32413550247722622, 207420591733202421

Offset

0,3

Links

Table of n, a(n) for n=0..24.

Formula

a(n) = Sum_{k=0..floor(n/3)} binomial(3*n-9*k+1,k) * binomial(3*n-9*k+1,n-3*k)/(3*n-9*k+1).

Prog

(PARI) a(n) = sum(k=0, n\3, binomial(3*n-9*k+1, k)*binomial(3*n-9*k+1, n-3*k)/(3*n-9*k+1));

Crossrefs

Cf. A200725, A364336, A379160.

Cf. A364329.

Sequence in context: A151233 A151234 A330799 * A367057 A317776 A145942

Adjacent sequences: A379156 A379157 A379158 * A379160 A379161 A379162

Keyword

nonn

Author

Seiichi Manyama, Dec 17 2024

Status

approved