A135864 G.f. A(x) satisfies A(x) = 1 + 9*x*A(x)^(1/3).

1, 9, 27, 0, -81, 243, 0, -2916, 10935, 0, -168399, 682344, 0, -11711385, 49364964, 0, -900438201, 3887490915, 0, -73729998576, 323480165085, 0, -6303914878248, 27978933759300, 0, -556251967191492, 2490404893915293, 0, -50276620111538700, 226626845346291663, 0

Offset: 0

Author

Paul D. Hanna, Dec 02 2007

Keywords

• sign

Crossrefs

Cf. A135863, A135866, A214668.

Programs

PARI

a(n)=9^n*binomial(n/3,n)/(1-2*n/3)

Formula

a(n) = -9^n*binomial(n/3,n)/(2n/3 - 1).

G.f. A(x) satisfies A(x) = 1/A(-x*A(x)^(-1/3)). - Seiichi Manyama, Jun 18 2025