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A161798
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G.f. satisfies: A(x) = 1/(1 - x/(1 - x*A(x))^3)^2.
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1
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1, 2, 9, 46, 262, 1590, 10081, 65986, 442518, 3024772, 20996141, 147603198, 1048747751, 7519252606, 54332565330, 395264527626, 2892666314150, 21281120904168, 157299607827727, 1167582500757800, 8699515577902203
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OFFSET
| 0,2
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FORMULA
| a(n) = Sum_{k=0..n} C(2*n-k+1,k)/(n-k+1) * C(n+2*k-1,n-k).
Let A(x)^m = Sum_{n>=0} a(n,m)*x^n then
a(n,m) = Sum_{k=0..n} C(2*n-k+m,k)*m/(n-k+m) * C(n+2*k-1,n-k).
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PROG
| (PARI) {a(n, m=1)=sum(k=0, n, binomial(2*n-k+m, k)*m/(n-k+m)*binomial(n+2*k-1, n-k))}
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CROSSREFS
| Cf. A161797, A161799.
Sequence in context: A036726 A020053 A114194 * A134091 A183166 A032331
Adjacent sequences: A161795 A161796 A161797 * A161799 A161800 A161801
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KEYWORD
| nonn
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AUTHOR
| Paul D. Hanna (pauldhanna(AT)juno.com), Jun 19 2009
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