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A076126
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Triangle T(n,k) of associated Lah numbers, n>=2, k=1..floor(n/2).
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0
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2, 6, 24, 12, 120, 120, 720, 1080, 120, 5040, 10080, 2520, 40320, 100800, 40320, 1680, 362880, 1088640, 604800, 60480, 3628800, 12700800, 9072000, 1512000, 30240, 39916800, 159667200, 139708800, 33264000, 1663200, 479001600
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OFFSET
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2,1
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COMMENTS
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Number of partitions of {1,..,n} into k lists of size >1, where a list means an ordered subset, cf. A008297.
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LINKS
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Table of n, a(n) for n=2..32.
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FORMULA
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T(n, k) = n!/k!*binomial(n-k-1, k-1), n>=2, k=1..floor(n/2). G.f.: G.f.: Sum_{n>=2, k=1..floor(n/2)} T(n, k)*x^n*y^k/n! = exp(x^2*y/(1-x))-1.
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EXAMPLE
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2; 6; 24, 12; 120,120; 720,1080,120; 5040,10080, 2520; ...
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CROSSREFS
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Row sums give A052845, A008306, A008299.
Sequence in context: A243657 A321475 A004154 * A263692 A319544 A354833
Adjacent sequences: A076123 A076124 A076125 * A076127 A076128 A076129
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KEYWORD
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nonn,tabf
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AUTHOR
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Vladeta Jovovic, Vladimir Baltic, Oct 31 2002
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STATUS
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approved
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