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A038372
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Largest subset of integers [ 1...n ] such that no member divides two others.
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0
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1, 2, 2, 3, 4, 4, 5, 6, 6, 7, 8, 8, 9, 10, 10, 11, 12, 12, 13, 14, 14, 15, 16, 16, 17, 18, 19, 20, 21, 21, 22, 22, 22, 23, 24, 24, 25, 26, 26, 27, 28, 28, 29, 30
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OFFSET
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1,2
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REFERENCES
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R. K. Guy, Unsolved Problems Number Theory, B24.
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LINKS
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FORMULA
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a(n) >= ceiling(2n/3). For large n, 0.6725n <= a(n) <= 0.6736n (see Guy).
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EXAMPLE
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{6,8-17,19-23,25-29} is the largest set of positive integers <= 29 such that none of them divides two of the others. The cardinality of the set is 21, so a(29)=21.
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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More terms and additional comments from Jud McCranie, Jan 17 2001
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STATUS
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approved
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