A371989 G.f. A(x) satisfies A(x) = ( 1 + 9*x*A(x)*(1 + A(x)) )^(1/3).

1, 6, 18, -18, -270, 486, 7938, -17010, -290142, 676998, 11852082, -29091474, -518183406, 1315388646, 23720180130, -61672468338, -1122411776958, 2971089997830, 54459919690578, -146181889695762, -2694816626063310, 7314502270743270, 135469313469987138

Offset

0,2

Links

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

Formula

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

Prog

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

Crossrefs

Cf. A000302, A371990.

Cf. A371681.

Sequence in context: A223218 A077630 A361730 * A045857 A074791 A093106

Adjacent sequences: A371986 A371987 A371988 * A371990 A371991 A371992

Keyword

sign

Author

Seiichi Manyama, Apr 15 2024

Status

approved