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A071210
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Triangular array T(n,k) read by rows, giving number of labeled free trees such that the root is smaller than all its children, with respect to the number n of vertices and to the degree k of the root.
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0
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1, 3, 1, 18, 8, 1, 160, 80, 15, 1, 1875, 1000, 225, 24, 1, 27216, 15120, 3780, 504, 35, 1, 470596, 268912, 72030, 10976, 980, 48, 1, 9437184, 5505024, 1548288, 258048, 26880, 1728, 63, 1, 215233605, 127545840, 37200870, 6613488, 765450, 58320
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OFFSET
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1,2
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LINKS
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FORMULA
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T(n,k) = binomial(n+1, k+1)*k*n^(n-k-1).
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MAPLE
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(n, k) -> binomial(n+1, k+1)*k*n^(n-k-1)
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PROG
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(PARI) tabl(nn) = for (n=1, nn, for (k=1, n, print1(binomial(n+1, k+1)*k*n^(n-k-1), ", "); ); print) \\ Michel Marcus, Jun 27 2013
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CROSSREFS
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KEYWORD
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AUTHOR
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Cedric Chauve (chauve(AT)lacim.uqam.ca), May 16 2002
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STATUS
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approved
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