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A365121
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G.f. satisfies A(x) = (1 + x / (1 - x*A(x))^2)^3.
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3
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1, 3, 9, 40, 192, 993, 5375, 30081, 172650, 1010640, 6010530, 36214656, 220590082, 1356131892, 8403647454, 52436122717, 329170499604, 2077465903503, 13173914483799, 83897445169341, 536355204428412, 3440875097256529, 22144300030907667
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OFFSET
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0,2
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LINKS
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FORMULA
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If g.f. satisfies A(x) = (1 + x/(1 - x*A(x))^s)^t, then a(n) = Sum_{k=0..n} binomial(t*(n-k+1),k) * binomial(n+(s-1)*k-1,n-k)/(n-k+1).
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PROG
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(PARI) a(n, s=2, t=3) = sum(k=0, n, binomial(t*(n-k+1), k)*binomial(n+(s-1)*k-1, n-k)/(n-k+1));
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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