A366084 Expansion of (1/x) * Series_Reversion( x*(1-x)^3/(1-x-x^3) ).
1, 2, 7, 29, 132, 637, 3199, 16536, 87366, 469556, 2558610, 14100033, 78437805, 439838596, 2483300228, 14103794518, 80517436710, 461768157262, 2658979794811, 15366500638407, 89093023210674, 518064484263918, 3020484579372765, 17653011431832906
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(3*n-2*k+1, n-3*k))/(n+1);
Formula
a(n) = (1/(n+1)) * Sum_{k=0..floor(n/3)} (-1)^k * binomial(n+1,k) * binomial(3*n-2*k+1,n-3*k).