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Search: id:A133709
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| A133709 |
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Triangle read by rows: T(m,l) = number of labeled covers of size l of a finite set of m unlabeled elements (m >= 1, 1 <= l <= 2^m - 1). |
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6
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| 1, 1, 3, 3, 1, 7, 35, 140, 420, 840, 840, 1, 12, 131, 1435, 15225, 150570, 1351770
(list; graph; listen)
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OFFSET
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1,3
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REFERENCES
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A. P. Burger and J. H. van Vuuren, Balanced minimal covers of a finite set, Discr. Math. 307 (2007), 2853-2860.
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FORMULA
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Burger and van Vuuren give an explicit formula.
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EXAMPLE
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Triangle begins:
1
1 3 3
1 7 35 140 420 840 840
1 12 131 1435 15225 150570 1351770
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CROSSREFS
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Columns are given by A055998, A133710-A133712.
Sequence in context: A118408 A079268 A102316 this_sequence A124040 A078033 A108075
Adjacent sequences: A133706 A133707 A133708 this_sequence A133710 A133711 A133712
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KEYWORD
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nonn,tabf
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AUTHOR
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njas, Dec 30 2007
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