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Search: id:A038510
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| A038510 |
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Composite numbers with smallest prime factor >= 7. |
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+0
1
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| 49, 77, 91, 119, 121, 133, 143, 161, 169, 187, 203, 209, 217, 221, 247, 253, 259, 287, 289, 299, 301, 319, 323, 329, 341, 343, 361, 371, 377, 391, 403, 407, 413, 427, 437, 451, 469, 473, 481, 493, 497, 511, 517, 527, 529, 533, 539, 551, 553, 559, 581, 583
(list; graph; listen)
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OFFSET
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0,1
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COMMENT
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Let A = set of numbers of form 6n + 1, B = numbers of form 6n - 1. Eliminating numbers of form 25 + 30s from A and those of form 35 + 30s from B we obtain sets A* and B*. Removing all terms of the sequence from the union of A* and B*, only prime numbers remain. - Hisanobu Shinya (ilikemathematics(AT)hotmail.com), Jul 14 2002
Divide n by a*b*c where a = 2^(A001511(n)-1), b = 3^(A051064(n)-1) and c = 5^(A055457(n) -1). Then the resulting sequence includes only primes and a(n). - Alford Arnold (alford1940(AT)aol.com), Sep 08 2003
Composite numbers not divisible by 2, 3 or 5. - Lekraj Beedassy (blekraj(AT)yahoo.com), Jun 30 2004
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REFERENCES
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J. H. Silverman, A Friendly Introduction to Number Theory, 2nd Edn."Appendix A:Factorization of Small Composite Integers", Prentice Hall NY 2001.
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CROSSREFS
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Cf. A001511, A051064, A055457.
Sequence in context: A137558 A112074 A112057 this_sequence A063163 A103216 A036307
Adjacent sequences: A038507 A038508 A038509 this_sequence A038511 A038512 A038513
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KEYWORD
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nonn
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AUTHOR
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Jeff Burch (gburch(AT)erols.com)
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EXTENSIONS
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Corrected by Ralf Stephan (ralf(AT)ark.in-berlin.de), Apr 04 2003
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