A373544 - OEIS

A373544

Expansion of 1/(1 - x/(1 - 9*x^3)^(2/3)).

1, 1, 1, 1, 7, 13, 19, 70, 157, 280, 799, 1894, 3781, 9646, 23080, 49159, 119203, 283972, 627760, 1487095, 3518617, 7945561, 18620746, 43801447, 100117099, 233475802, 546859390, 1258634440, 2928668632, 6839770279, 15804569341, 36739434904, 85640217781, 198337427839

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OFFSET

0,5

LINKS

Table of n, a(n) for n=0..33.

FORMULA

a(n) = Sum_{k=0..floor(n/3)} 9^k * binomial(2*n/3-k-1,k).

a(n) == 1 (mod 3).

PROG

(PARI) a(n) = sum(k=0, n\3, 9^k*binomial(2*n/3-k-1, k));

CROSSREFS

Cf. A362210, A373543.