A366089 Expansion of (1/x) * Series_Reversion( x*(1-x)^3/(1-x-x^4) ).
1, 2, 7, 30, 142, 715, 3756, 20349, 112864, 637659, 3656775, 21229923, 124531256, 736920158, 4393859967, 26371222935, 159193382812, 965923527255, 5887659026592, 36034716884127, 221362690616841, 1364404640452602, 8435444693847402
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\4, (-1)^k*binomial(n+1, k)*binomial(3*n-3*k+1, n-4*k))/(n+1);
Formula
a(n) = (1/(n+1)) * Sum_{k=0..floor(n/4)} (-1)^k * binomial(n+1,k) * binomial(3*n-3*k+1,n-4*k).