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A051754
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Consider problem of placing N queens on an n X n board so that each queen attacks precisely 1 other. Sequence gives maximal number of queens.
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13
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2, 2, 4, 4, 8, 8, 10, 12, 12, 14, 16, 16, 18, 20, 20, 22, 24, 24, 26, 28, 28, 30, 32, 32, 34, 36, 36, 38, 40, 40, 42, 44, 44, 46, 48, 48, 50, 52, 52, 54, 56, 56, 58, 60, 60, 62, 64, 64, 66, 68, 68, 70, 72, 72, 74, 76, 76, 78, 80, 80, 82, 84, 84, 86
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OFFSET
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2,1
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COMMENTS
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2*[2n/3] is an upper bound for a(n). - Jud McCranie, Aug 12 2001
This bound is achieved for n=2, 4 and 6-65.
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REFERENCES
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Martin Gardner, The Last Recreations, Copernicus, NY, 1997, 274-283.
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LINKS
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CROSSREFS
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KEYWORD
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nonn,nice,more
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AUTHOR
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Robert Trent (trentrd(AT)hotmail.com), Aug 23 2000
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EXTENSIONS
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STATUS
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approved
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