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Search: id:A140711
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| A140711 |
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Triangle read by rows: T(n,k) is the number of permutations of {1,2,...,n} having k white corners (0<=k<=n-1; for definition see the Eriksson-Linusson references). |
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+0
3
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| 1, 1, 1, 1, 4, 1, 1, 10, 12, 1, 1, 20, 62, 36, 1
(list; table; graph; listen)
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OFFSET
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1,5
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COMMENT
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Sum of entries in row n is n! (A000142).
Sum(k*T(n,k),k=0..n-1)=A140712(n).
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REFERENCES
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K. Eriksson and S. Linusson, The size of Fulton's essential set, Electronic J. Combinatorics, Vol. 2, #R6, 1995.
K. Eriksson and S. Linusson. Combinatorics of Fulton's essential set. Duke Mathematical Journal 85(1):61-76, 1996.
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EXAMPLE
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Triangle starts:
1;
1,1;
1,4,1;
1,10,12,1;
1,20,62,36,1;
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CROSSREFS
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Cf. A000142, A140712.
Sequence in context: A082680 A056939 A142595 this_sequence A164366 A121692 A145271
Adjacent sequences: A140708 A140709 A140710 this_sequence A140712 A140713 A140714
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KEYWORD
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more,nonn,tabl
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AUTHOR
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Emeric Deutsch (deutsch(AT)duke.poly.edu), May 28 2008
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