A381945 G.f. A(x) satisfies A(x) = B(x*A(x)) / (1 - x)^2, where B(x) is the g.f. of A002293.
1, 3, 12, 79, 695, 6961, 74679, 837336, 9689234, 114822820, 1386402276, 16994276781, 210919650044, 2645218761934, 33470438908615, 426758782807956, 5477657372957314, 70720821402587371, 917801926609131194, 11966203939448781600, 156662012236067711036, 2058709975008385135863
Offset: 0
Keywords
Programs
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PARI
a(n) = sum(k=0, n, binomial(5*k+1, k)*binomial(n+k+1, n-k)/(5*k+1));
Formula
a(n) = Sum_{k=0..n} binomial(5*k+1,k) * binomial(n+k+1,n-k)/(5*k+1).