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Search: id:A137973
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| A137973 |
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G.f. satisfies A(x) = 1 + x*(1 + x*A(x)^6)^5. |
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+0
6
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| 1, 1, 5, 40, 355, 3495, 36251, 391650, 4355810, 49550130, 573811635, 6742112506, 80175836395, 963137138105, 11670425726255, 142471372540290, 1750641388279500, 21634966222174020, 268734270298502640
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OFFSET
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0,3
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FORMULA
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G.f.: A(x) = 1 + x*B(x)^5 where B(x) is the g.f. of A137974.
a(n) = Sum_{k=0..n-1} C(5*(n-k),k)/(n-k) * C(6*k,n-k-1) for n>0 with a(0)=1. [From Paul D. Hanna (pauldhanna(AT)juno.com), Jun 16 2009]
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PROGRAM
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(PARI) {a(n)=local(A=1+x*O(x^n)); for(i=0, n, A=1+x*(1+x*A^6)^5); polcoeff(A, n)}
(PARI) a(n)=if(n==0, 1, sum(k=0, n-1, binomial(5*(n-k), k)/(n-k)*binomial(6*k, n-k-1))) [From Paul D. Hanna (pauldhanna(AT)juno.com), Jun 16 2009]
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CROSSREFS
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Cf. A137974, A137972; A137961, A137963, A137965.
Sequence in context: A027259 A007036 A052798 this_sequence A052788 A130564 A124555
Adjacent sequences: A137970 A137971 A137972 this_sequence A137974 A137975 A137976
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), Feb 26 2008
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