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A086922
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Number of idempotent n X n (0,1) matrices over the reals.
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1
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OFFSET
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0,2
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COMMENTS
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Let m(n,k) be the number of idempotent n X n (0,1) matrices with k entries equal to 1. Then:
k | m(n,k)
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0 | 1
1 | n
4 | ((n - 3) (n - 2) (n - 1) (35 n - 124))/8
5 | ((n - 4) (n - 3) (n - 2) (n - 1) (631 n - 2675))/120
...
Conjecture: There is no closed form expression for this sequence.
(End)
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LINKS
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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Yuval Dekel (dekelyuval(AT)hotmail.com), Sep 19 2003
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EXTENSIONS
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STATUS
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approved
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