A366085 Expansion of (1/x) * Series_Reversion( x*(1-x)^4/(1-x-x^3) ).
1, 3, 15, 90, 596, 4199, 30869, 234091, 1817720, 14380288, 115492518, 939163680, 7717237661, 63979604459, 534498370665, 4495171005567, 38026764744348, 323358790454352, 2762410748226232, 23697028402783512, 204044822552956179, 1762917281476448944
Offset: 0
Keywords
Links
- Seiichi Manyama, Table of n, a(n) for n = 0..1000
Programs
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PARI
a(n) = sum(k=0, n\3, (-1)^k*binomial(n+1, k)*binomial(4*n-2*k+2, n-3*k))/(n+1);
Formula
a(n) = (1/(n+1)) * Sum_{k=0..floor(n/3)} (-1)^k * binomial(n+1,k) * binomial(4*n-2*k+2,n-3*k).