A383611 Expansion of 1/( (1-x^3) * (1-x^3-9*x)^2 )^(1/3).
1, 6, 45, 361, 2982, 25083, 213499, 1832508, 15827103, 137356597, 1196642427, 10457750151, 91630781245, 804632867643, 7078961780064, 62380210284379, 550478616300900, 4863816606663882, 43022548851457447, 380930792260360182, 3375853250109410583
Offset: 0
Keywords
Programs
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PARI
a(n) = sum(k=0, n\3, (-9)^(n-3*k)*binomial(-2/3, n-3*k)*binomial(n-2*k, k));
Formula
a(n) = Sum_{k=0..floor(n/3)} (-9)^(n-3*k) * binomial(-2/3,n-3*k) * binomial(n-2*k,k).