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Search: id:A140712
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| A140712 |
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Number of white corners in all permutations of {1,2,...,n} (for definition see the Eriksson-Linusson references). |
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+0
3
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| 0, 1, 6, 37, 256, 2000, 17520, 170520, 1827840, 21409920, 272160000, 3732220800, 54925516800, 863480217600, 14442536908800, 256086230400000, 4798293147648000, 94731418349568000, 1965528727658496000
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OFFSET
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1,3
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COMMENT
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a(n)=Sum(k*A140711(n,k),k=0..n-1).
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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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FORMULA
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a(n)=(n-1)![binom(n-1,3)+6*binom(n,2)]/6=(n-1)!*(n-1)*(n^2+13n+6)/36.
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MAPLE
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seq((1/36)*(n-1)*factorial(n-1)*(n^2+13*n+6), n=1..20);
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CROSSREFS
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Cf. A000142, A140711.
Sequence in context: A005389 A080954 A073013 this_sequence A079751 A088312 A012364
Adjacent sequences: A140709 A140710 A140711 this_sequence A140713 A140714 A140715
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KEYWORD
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nonn
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AUTHOR
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Emeric Deutsch (deutsch(AT)duke.poly.edu), May 28 2008
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