A373714 Expansion of 1/(2 - (1 + 9*x)^(2/3)).
1, 6, 27, 144, 648, 3564, 15066, 91368, 325863, 2519910, 5487183, 80131680, -19315584, 3165288840, -10368295812, 157258666944, -910416537216, 9230359934844, -66824394346314, 594882273889656, -4709265051598938, 40223940845756976, -330361209519974280
Offset: 0
Keywords
Programs
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PARI
my(N=30, x='x+O('x^N)); Vec(1/(2-(1+9*x)^(2/3)))
Formula
a(n) = 9^n * Sum_{k>=0} (1/2)^(k+1) * binomial(2*k/3,n).