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Search: id:A007916
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| 2, 3, 5, 6, 7, 10, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 22, 23, 24, 26, 28, 29, 30, 31, 33, 34, 35, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 82, 83
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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These can be computed with a modified Sieve of Eratosthenes: (1) start at n=2 (2) if n is not crossed out, then append n to the sequence and cross out all powers of n (3) set n = n+1 and go to step 2 - Sam Alexander (amnalexander(AT)yahoo.com), Dec 15 2003
A075802(a(n)) = 0. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Mar 19 2009]
Or, the numbers with an even number of divisors. - Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Oct 10 2009
The previous comment is wrong. For example, 27 has 4 divisors, but 27 is not in this sequence. [From T. D. Noe (noe(AT)sspectra.com), Nov 11 2009]
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REFERENCES
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F. Smarandache, "Only Problems, not Solutions!", Xiquan Publ., Phoenix-Chicago, 1993
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LINKS
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N. J. A. Sloane, Table of n, a(n) for n = 1..9875
F. Smarandache, Only Problems, Not Solutions!.
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MATHEMATICA
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a = {}; Do[If[Apply[GCD, Transpose[FactorInteger[n]][[2]]] == 1, a = Append[a, n]], {n, 2, 200}]; a
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PROGRAM
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(MAGMA) [n : n in [2..1000] | not IsPower(n) ];
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CROSSREFS
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Complement of A001597. Union of A052485 and A052486.
A144338. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Mar 19 2009]
Cf. A000005. [From Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Oct 10 2009]
Sequence in context: A028769 A094784 A085971 this_sequence A052485 A109421 A065872
Adjacent sequences: A007913 A007914 A007915 this_sequence A007917 A007918 A007919
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KEYWORD
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nonn,new
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AUTHOR
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R. Muller
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EXTENSIONS
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More terms from Henry Bottomley (se16(AT)btinternet.com), Sep 12 2000
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