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 A079772 Let C(n) be the n-th composite number; then a(n) is the smallest number > C(n) and not coprime to C(n). 0
 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; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(n) = A002808(n) + A056608(n). - Vladeta Jovovic, Jan 31 2003 LINKS Table of n, a(n) for n=1..70. FORMULA a(n) = C(n) + smallest prime divisor of C(n). EXAMPLE 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 PROG (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); ) ) } CROSSREFS Sequence in context: A171562 A018221 A071278 * A080731 A080257 A331201 Adjacent sequences: A079769 A079770 A079771 * A079773 A079774 A079775 KEYWORD nonn AUTHOR Amarnath Murthy, Jan 31 2003 EXTENSIONS More terms from Cino Hilliard, Aug 12 2003 STATUS approved

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Last modified August 11 01:05 EDT 2024. Contains 375059 sequences. (Running on oeis4.)