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Search: id:A087087
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| A087087 |
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Coprime subsets of the integers 1 to n, each subset mapped onto a unique binary integer, values here shown in decimal. |
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+0
1
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| 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 13, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 28, 29, 32, 33, 48, 49, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 76, 77, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 92, 93, 96, 97, 112, 113, 128, 129, 132, 133, 144, 145, 148, 149, 192, 193, 196, 197
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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A coprime set of integers has no pair of elements for which (i,j)=0. Each element i in a subset contributes 2^(i-1) to the binary value for that subset. The integers missing from the sequence correspond to non-coprime subsets.
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REFERENCES
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Alan Sutcliffe, Divisors and Common Factors in Sets of Integers, awaiting publication.
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EXAMPLE
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a(11)=13 since the 11th coprime set counting from 0 is (4,3,1), which maps onto 1101 binary = 13 decimal.
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CROSSREFS
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A087086 gives the corresponding values for the primitive sets of integers. A084422 gives the number of coprime subsets of the integers 1 to n.
Sequence in context: A069784 A048097 A130843 this_sequence A050742 A111228 A107743
Adjacent sequences: A087084 A087085 A087086 this_sequence A087088 A087089 A087090
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KEYWORD
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easy,nonn
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AUTHOR
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Alan Sutcliffe (alansut(AT)ntlworld.com), Aug 16 2003
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