A366697 G.f. satisfies A(x) = (1 + x)^3 + x*A(x)^3.

1, 4, 15, 94, 706, 5769, 49923, 449376, 4164228, 39459852, 380594767, 3724049805, 36876008673, 368835076813, 3720863181033, 37815675159285, 386818379566749, 3979362306753315, 41144521893563511, 427335033811660713, 4456402044181677264

Offset

0,2

Links

Table of n, a(n) for n=0..20.

Formula

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

Prog

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

Crossrefs

Cf. A366266, A366696.

Cf. A364623.

Sequence in context: A332533 A013193 A040025 * A208991 A109365 A352415

Adjacent sequences: A366694 A366695 A366696 * A366698 A366699 A366700

Keyword

nonn

Author

Seiichi Manyama, Oct 16 2023

Status

approved