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Search: id:A137965
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| A137965 |
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G.f. satisfies A(x) = 1 + x*(1 + x*A(x)^4)^5. |
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+0
6
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| 1, 1, 5, 30, 220, 1725, 14356, 124020, 1102770, 10023680, 92722620, 870039474, 8261024380, 79225392830, 766302511445, 7466883915800, 73227699088806, 722228333119200, 7159117292177840, 71284856957207030, 712673042497177450
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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 A137964.
a(n) = Sum_{k=0..n-1} C(5*(n-k),k)/(n-k) * C(4*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^4)^5); polcoeff(A, n)}
(PARI) a(n)=if(n==0, 1, sum(k=0, n-1, binomial(5*(n-k), k)/(n-k)*binomial(4*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. A137964, A137966; A137961, A137963, A137973.
Sequence in context: A001720 A051829 A058247 this_sequence A129695 A110521 A144498
Adjacent sequences: A137962 A137963 A137964 this_sequence A137966 A137967 A137968
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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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