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Search: id:A120022
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| A120022 |
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a(n) = A120020(n)/n = coefficient of x^n in the n-th self-composition of the g.f. of A120010, divided by n, for n>=1. |
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+0
3
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| 1, 1, 3, 17, 142, 1558, 21155, 342584, 6448217, 138392304, 3336869488, 89325958048, 2629214627421, 84408934941424, 2935694381925743, 109967573757472768, 4414292541216287516, 189054708982869449056
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OFFSET
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1,3
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PROGRAM
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(PARI) {a(n)=polcoeff((1-sqrt(1-4*x*(1-x)/(1-(n+1)*x*(1-x)+x*O(x^n))))/2, n)/n} (PARI) /* Alternate Formula: */ {a(n)=sum(j=1, n, binomial(2*n-2*j, n-j)/(n-j+1)* sum(i=1, j, (-1)^(j-i)*binomial(n-j+i, j-i)*binomial(n-j+i-1, i-1)*n^(i-2)))}
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CROSSREFS
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Cf. A120010, A120019, A120020, A120021; A120016.
Sequence in context: A060003 A025167 A136727 this_sequence A001865 A087885 A051442
Adjacent sequences: A120019 A120020 A120021 this_sequence A120023 A120024 A120025
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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), Jun 14 2006
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