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Search: id:A074828
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| A074828 |
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a(1) = 1; for n>1, a(n) = smallest composite multiple of n if n is a prime else the smallest prime divisor of n if n is composite. |
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2
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| 1, 4, 6, 2, 10, 2, 14, 2, 3, 2, 22, 2, 26, 2, 3, 2, 34, 2, 38, 2, 3, 2, 46, 2, 5, 2, 3, 2, 58, 2, 62, 2, 3, 2, 5, 2, 74, 2, 3, 2, 82, 2, 86, 2, 3, 2, 94, 2, 7, 2, 3, 2, 106, 2, 5, 2, 3, 2, 118, 2, 122, 2, 3, 2, 5, 2, 134, 2, 3, 2, 142, 2, 146, 2, 3, 2, 7, 2, 158, 2, 3, 2, 166, 2, 5, 2, 3, 2, 178, 2
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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a(n) = 2n if n is a prime, a(2n+2) = 2.
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PROGRAM
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(PARI) print1("1, "); for(n=2, 100, if(isprime(n), print1(2*n, ", "), print1(factor(n)[1, 1], ", "))) (Rick L. Shepherd)
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CROSSREFS
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Sequence in context: A114579 A021220 A095196 this_sequence A159193 A118967 A059030
Adjacent sequences: A074825 A074826 A074827 this_sequence A074829 A074830 A074831
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Sep 13 2002
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EXTENSIONS
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More terms from Rick L. Shepherd (rshepherd2(AT)hotmail.com), Jun 07 2004
Entry revised by N. J. A. Sloane (njas(AT)research.att.com), Aug 13 2006
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