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A087086
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Primitive subsets of the integers 1 to n, each subset mapped onto a unique binary integer, values here shown in decimal.
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1
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0, 1, 2, 4, 6, 8, 12, 16, 18, 20, 22, 24, 28, 32, 40, 48, 56, 64, 66, 68, 70, 72, 76, 80, 82, 84, 86, 88, 92, 96, 104, 112, 120, 128, 132, 144, 148, 160, 176, 192, 196, 208, 212, 224, 240, 256, 258, 264, 272, 274, 280, 288, 296, 304, 312, 320, 322, 328, 336, 338, 344
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| A primitive set of integers has no pair of elements one of which divides the other. 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 nonprimitive subsets.
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REFERENCES
| Alan Sutcliffe, Divisors and Common Factors in Sets of Integers, awaiting publication
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EXAMPLE
| a(10)=22 since the 10th primitive set counting from 0 is (5,3,2), which maps onto 10110 binary = 22 decimal.
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CROSSREFS
| Cf. A051026 gives the number of primitive subsets of the integers 1 to n.
Sequence in context: A090404 A015937 A058825 * A103288 A125225 A092903
Adjacent sequences: A087083 A087084 A087085 * A087087 A087088 A087089
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KEYWORD
| easy,nonn
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AUTHOR
| Alan Sutcliffe (alansut(AT)ntlworld.com), Aug 14 2003
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