A372022 G.f. A(x) satisfies A(x) = ( 1 + 9*x/(1 - x*A(x))^2 )^(1/3).

1, 3, -3, 36, -150, 1131, -6975, 50349, -353001, 2598993, -19218273, 145002066, -1103619348, 8494014009, -65879935581, 514828933092, -4048045183590, 32008577419905, -254337177982545, 2029871382481236, -16264438160161098, 130785869141097201

Offset

0,2

Links

Table of n, a(n) for n=0..21.

Formula

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

Prog

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

Crossrefs

Cf. A372021.

Sequence in context: A213281 A303820 A206477 * A219210 A218863 A082394

Adjacent sequences: A372019 A372020 A372021 * A372023 A372024 A372025

Keyword

sign

Author

Seiichi Manyama, Apr 16 2024

Status

approved