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Search: id:A005097
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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
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Or, 2n+1 is prime.
Also numbers not of the form 2xy+x+y. - Jose Brox (tautocrona(AT)terra.es), Dec 29 2005
This sequence arises if you factor the product of a large number of the first odd numbers into the form 3^n(3)5^n(5)7^n(7)11^n(11)... Then n(3)/n(5) = 2, n(3)/n(7) = 3, n(3)/n(11) = 5,... . - Andrzej Staruszkiewicz (astar(AT)th.if.uj.edu.pl), May 31 2007
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REFERENCES
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Dhananjay P. Mehendale, On Hamilton Decompositions, arxiv.org/pdf/0806.0251
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..1000
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FORMULA
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a(n) = A006093(n)/2 = A000010[A000040(n)]/2
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MATHEMATICA
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Table[p=Prime[n]; (p-1)/2, {n, 2, 22}] (from Vladimir Orlovsky (4vladimir(AT)gmail.com), Apr 29 2008)
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CROSSREFS
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Complement of A047845. Cf. A000040, A006005, A006093.
A130290 is an essentially identical sequence.
Sequence in context: A082583 A130290 A102781 this_sequence A111332 A139791 A027563
Adjacent sequences: A005094 A005095 A005096 this_sequence A005098 A005099 A005100
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KEYWORD
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nonn,easy
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AUTHOR
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njas
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