A373543 Expansion of 1/(1 - x/(1 - 9*x^2)^(2/3)).

1, 1, 1, 7, 13, 64, 151, 634, 1693, 6514, 18688, 68239, 204631, 722920, 2230498, 7711216, 24246229, 82612189, 263112874, 887565955, 2852058448, 9553983613, 30892668295, 102975387211, 334454025715, 1110899344549, 3619669508056, 11992016509234, 39164977065622

Offset

0,4

Links

Table of n, a(n) for n=0..28.

Formula

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

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

Prog

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

Crossrefs

Cf. A362210, A373544.

Cf. A371456.

Sequence in context: A334794 A325029 A159198 * A106976 A219908 A098478

Adjacent sequences: A373540 A373541 A373542 * A373544 A373545 A373546

Keyword

nonn

Author

Seiichi Manyama, Jun 09 2024

Status

approved