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Search: id:A079772
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| A079772 |
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Let C(n) be the n-th composite number; then a(n) is the smallest number > C(n) and not coprime to C(n). |
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+0
1
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| 6, 8, 10, 12, 12, 14, 16, 18, 18, 20, 22, 24, 24, 26, 30, 28, 30, 30, 32, 34, 36, 36, 40, 38, 40, 42, 42, 44, 46, 48, 48, 50, 56, 52, 54, 54, 56, 60, 58, 60, 60, 62, 64, 66, 66, 70, 68, 70, 72, 72, 74, 76, 78, 78, 84, 80, 82, 84, 84, 86, 90, 88, 90, 90, 92, 98, 94, 96, 96, 100
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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a(n) = A002808(n) + A056608(n). - Vladeta Jovovic (vladeta(AT)Eunet.yu), Jan 31 2003
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FORMULA
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a(n) = C(n) + smallest prime divisor of C(n).
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EXAMPLE
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C(4) = 9 and C(5) = 10 hence a(4) = a(5) = 12.
For 91=7*13 we have 91+7 = 98; for 92=2*2*23 we have 92-2 = 94
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PROGRAM
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(PARI) cminusp31(n) = \sum c+min prime div { for(x=2, n, forprime(p=2, floor(sqrt(x)), if(x%p==0 & isprime(x)==0, print1(x+p, ", "); break); ) ) }
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CROSSREFS
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Adjacent sequences: A079769 A079770 A079771 this_sequence A079773 A079774 A079775
Sequence in context: A138890 A018221 A071278 this_sequence A080731 A080257 A050199
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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), Jan 31 2003
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EXTENSIONS
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More terms from Cino Hilliard (hillcino368(AT)gmail.com), Aug 12 2003
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