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Search: id:A038372
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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
1
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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
(list; graph; listen)
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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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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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Sequence in context: A020915 A032509 A004523 this_sequence A121930 A020909 A075357
Adjacent sequences: A038369 A038370 A038371 this_sequence A038373 A038374 A038375
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KEYWORD
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nonn
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AUTHOR
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John W. Layman (layman(AT)math.vt.edu)
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EXTENSIONS
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More terms and additional comments from Jud McCranie (j.mccranie(AT)comcast.net), Jan 17 2001
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