A379281 G.f. A(x) satisfies A(x) = 1/( (1 - x) * (1 - x*A(x)) )^2.

1, 4, 18, 96, 575, 3706, 25078, 175666, 1262723, 9261018, 69024147, 521281642, 3980391050, 30678331440, 238350850248, 1864751821958, 14678131286357, 116160233811868, 923684828888152, 7376541052964806, 59137050311947284, 475757909357776656, 3839678158239147611

Offset

0,2

Links

Table of n, a(n) for n=0..22.

Formula

G.f.: B(x)^2 where B(x) is the g.f. of A199475.

a(n) = 2 * Sum_{k=0..n} binomial(2*n-k+2,k) * binomial(3*n-3*k+1,n-k)/(2*n-k+2).

Prog

(PARI) a(n) = 2*sum(k=0, n, binomial(2*n-k+2, k)*binomial(3*n-3*k+1, n-k)/(2*n-k+2));

Crossrefs

Cf. A379282, A379283.

Cf. A199475.

Sequence in context: A005777 A180567 A378733 * A392210 A152392 A001563

Adjacent sequences: A379278 A379279 A379280 * A379282 A379283 A379284

Keyword

nonn

Author

Seiichi Manyama, Dec 19 2024

Status

approved