A365087 G.f. satisfies A(x) = 1 + x*A(x) / (1 + x*A(x))^4.
1, 1, -3, -1, 29, -44, -265, 1114, 1369, -19076, 20388, 250977, -875281, -2116594, 19136754, -7765108, -306092007, 830209808, 3388957208, -22266676364, -8185922076, 413223401045, -814031607979, -5513566634947, 27558060911119, 35395095404776
Offset: 0
Keywords
Programs
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PARI
a(n) = sum(k=0, n, (-1)^(n-k)*binomial(n, k)*binomial(n+3*k-1, n-k)/(n-k+1));
Formula
a(n) = Sum_{k=0..n} (-1)^(n-k) * binomial(n,k) * binomial(n+3*k-1,n-k) / (n-k+1).