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 A164276 The non-isolated nonprimes. 13
 0, 1, 8, 9, 10, 14, 15, 16, 20, 21, 22, 24, 25, 26, 27, 28, 32, 33, 34, 35, 36, 38, 39, 40, 44, 45, 46, 48, 49, 50, 51, 52, 54, 55, 56, 57, 58, 62, 63, 64, 65, 66, 68, 69, 70, 74, 75, 76, 77, 78, 80, 81, 82, 84, 85, 86, 87, 88, 90, 91, 92, 93, 94, 95, 96, 98, 99, 100, 104, 105, 106, 110 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Non-isolated nonprimes in the sense that at least one of the two adjacent integers is also a nonprime. LINKS G. C. Greubel, Table of n, a(n) for n = 1..1000 FORMULA A141468 \ A014574. a(n) = n + n / log n + O(n / (log n)^2) by Brun's theorem. - Charles R Greathouse IV, Mar 15 2011 MATHEMATICA Select[Range[0, 100], !PrimeQ[#] && (!PrimeQ[# - 1] || !PrimeQ[# + 1]) & ] (* G. C. Greubel, Jul 07 2016 *) PROG (PARI) isA164276(n) = !isprime(n)&&(!isprime(n-1)||!isprime(n+1)) \\ Michael B. Porter, Feb 02 2010 CROSSREFS Cf. A014574, A141468. Sequence in context: A067683 A338026 A359881 * A154967 A271211 A341044 Adjacent sequences: A164273 A164274 A164275 * A164277 A164278 A164279 KEYWORD nonn,easy AUTHOR Juri-Stepan Gerasimov, Aug 11 2009 EXTENSIONS 40 added by R. J. Mathar, Aug 27 2009 STATUS approved

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Last modified June 17 07:23 EDT 2024. Contains 373433 sequences. (Running on oeis4.)