A381786 G.f. A(x) satisfies A(x) = (1 + x) * C(x*A(x)^3), where C(x) is the g.f. of A000108.
1, 2, 9, 76, 744, 7986, 90836, 1075714, 13122656, 163769229, 2080985186, 26832199993, 350187469872, 4617094718728, 61406081813812, 822834184073768, 11098254270705028, 150555545320009712, 2052839917410937693, 28118478688846531072, 386727880988105218913, 5338557108832658927346
Offset: 0
Keywords
Programs
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PARI
a(n) = sum(k=0, n, binomial(5*k+1, k)*binomial(3*k+1, n-k)/(5*k+1));
Formula
a(n) = Sum_{k=0..n} binomial(5*k+1,k) * binomial(3*k+1,n-k)/(5*k+1).