A377238 Expansion of 1/(1 - 9*x/(1 - 9*x)^(1/3))^(1/3).
1, 3, 27, 288, 3267, 38232, 456030, 5511726, 67275765, 827544276, 10243778238, 127471232682, 1593323199828, 19992464465031, 251700257824749, 3178185350410386, 40235213754593325, 510553935341621550, 6492029680359751572, 82705296277037467728, 1055413999621027732986
Offset: 0
Keywords
Programs
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PARI
a(n) = 9^n*sum(k=0, n, (-1)^k*binomial(-1/3, k)*binomial(n-2*k/3-1, n-k));
Formula
a(n) = 9^n * Sum_{k=0..n} (-1)^k * binomial(-1/3,k) * binomial(n-2*k/3-1,n-k).