A381941 G.f. A(x) satisfies A(x) = (1 + x)^2 * B(x*A(x)), where B(x) is the g.f. of A002293.
1, 3, 10, 71, 644, 6461, 68971, 768054, 8820281, 103694479, 1241799996, 15095075897, 185769856443, 2310006893997, 28978952155943, 366315306556482, 4661272734504606, 59659914501348239, 767539555514812321, 9920124234695256009, 128744011085858468131, 1677087982747514335025
Offset: 0
Keywords
Programs
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PARI
a(n) = sum(k=0, n, binomial(5*k+1, k)*binomial(2*k+2, n-k)/(5*k+1));
Formula
a(n) = Sum_{k=0..n} binomial(5*k+1,k) * binomial(2*k+2,n-k)/(5*k+1).