A379286 G.f. A(x) satisfies A(x) = 1/((1 - x*A(x)^2) * (1 - x*A(x)^5)).
1, 2, 17, 209, 3025, 47975, 806673, 14126236, 254880645, 4705443504, 88458542000, 1687588704861, 32589587581341, 635824437818621, 12513756861585915, 248148065577971460, 4953215882123744005, 99442753396113435246, 2006704742456528041800, 40679834776076235917841
Offset: 0
Keywords
Programs
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PARI
a(n) = sum(k=0, n, binomial(2*n+4*k+1, k)*binomial(3*n+2*k, n-k)/(2*n+4*k+1));
Formula
a(n) = Sum_{k=0..n} binomial(2*n+4*k+1,k) * binomial(3*n+2*k,n-k)/(2*n+4*k+1).