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A139791
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Numbers n for which 2n is a multiple of A002326.
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0
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1, 2, 3, 5, 6, 8, 9, 11, 14, 15, 18, 20, 21, 23, 26, 29, 30, 33, 35, 36, 39, 41, 44, 48, 50, 51, 53, 54, 56, 63, 65, 68, 69, 74, 75, 78, 81, 83, 86, 89, 90, 95, 96, 98, 99, 105, 111, 113, 114, 116, 119, 120, 125, 128, 131, 134, 135, 138, 140, 141, 146, 153, 155, 156, 158
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| The sequence properly contains A005097. 170 is the first number which is not in A005097. One can prove that A002326(2^(2t-1))=4t. Thus if n=2^(2t-1), where, for any m>0, t=2^(m-1) then 2n is a multiple of A002326(n) while 2n+1 is a Fermat number which, as well known,is not always a prime.
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FORMULA
| The sequence is the union of A005097 and (A001567(n)-1)/2). [Conjectured by Vladimir Shevelev, proved by Ray Chandler May 26 2008]
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CROSSREFS
| Cf. A002326, A005097, A001262, A137576.
Sequence in context: A005097 A102781 * A147855 A027563 A000534 A136112
Adjacent sequences: A139788 A139789 A139790 * A139792 A139793 A139794
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KEYWORD
| nonn
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AUTHOR
| Vladimir Shevelev (shevelev(AT)bgu.ac.il), May 21 2008, May 24 2008
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