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Search: id:A066664
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| A066664 |
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Composite numbers n whose divisors less than or equal to sqrt(n) are consecutive, from 1 up to some number k. |
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+0
1
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| 4, 6, 8, 10, 12, 14, 18, 22, 24, 26, 34, 38, 46, 58, 60, 62, 74, 82, 86, 94, 106, 118, 122, 134, 142, 146, 158, 166, 178, 194, 202, 206, 214, 218, 226, 254, 262, 274, 278, 298, 302, 314, 326, 334, 346, 358, 362, 382, 386, 394, 398, 422, 446, 454, 458, 466, 478
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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The sequence consists of all numbers of the form 2p with p prime, along with 8, 12, 18, 24 and 60. See sketch of proof in A066522.
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MATHEMATICA
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a = {}; Do[ If[ !PrimeQ[n], k = Select[ Divisors[n], # <= Sqrt[n] &]; If[ Last[k] == Length[k], a = Append[a, n]]], {n, 1, 500} ]; a
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CROSSREFS
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These are the composite members of A066522.
Sequence in context: A134928 A141109 A061344 this_sequence A064938 A050990 A161546
Adjacent sequences: A066661 A066662 A066663 this_sequence A066665 A066666 A066667
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KEYWORD
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nice,nonn,easy
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AUTHOR
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Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 07 2002
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