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Search: id:A137964
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| A137964 |
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G.f. satisfies A(x) = 1 + x*(1 + x*A(x)^5)^4. |
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+0
6
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| 1, 1, 4, 26, 184, 1451, 12020, 103734, 921132, 8364877, 77317704, 725029730, 6880482816, 65955731874, 637703938860, 6211709281162, 60900108419200, 600486291654444, 5950951929703520, 59242473406384472, 592166933647780576
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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)^4 where B(x) is the g.f. of A137965.
a(n) = Sum_{k=0..n-1} C(4*(n-k),k)/(n-k) * C(5*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^5)^4); polcoeff(A, n)}
(PARI) a(n)=if(n==0, 1, sum(k=0, n-1, binomial(4*(n-k), k)/(n-k)*binomial(5*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. A137965, A137963; A137956, A137958, A137971.
Sequence in context: A084134 A098443 A052775 this_sequence A107649 A052763 A084211
Adjacent sequences: A137961 A137962 A137963 this_sequence A137965 A137966 A137967
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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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