A377261 Expansion of 1/(1 - 9*x*(1 + x))^(5/3).
1, 15, 195, 2340, 26910, 301158, 3307590, 35830080, 384072975, 4082949585, 43113860361, 452742067440, 4732188244290, 49266375442110, 511157395433610, 5287689996408612, 54555878321808435, 561579617798527185, 5768783256563735265, 59149668761521664040, 605472238745163334116
Offset: 0
Keywords
Programs
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PARI
a(n) = sum(k=0, n, (-9)^k*binomial(-5/3, k)*binomial(k, n-k));
Formula
a(n) = 3*((3*n+2)*a(n-1) + (3*n+4)*a(n-2))/n for n > 1.
a(n) = Sum_{k=0..n} (-9)^k * binomial(-5/3,k) * binomial(k,n-k).
a(n) ~ Gamma(1/3) * n^(2/3) * 3^(n + 3/2) * (3 + sqrt(13))^(n + 5/3) / (Pi * 13^(5/6) * 2^(n + 11/3)). - Vaclav Kotesovec, May 03 2025