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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
FORMULA
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
Sequence in context: A067683 A338026 A359881 * A154967 A271211 A341044
KEYWORD
nonn,easy
AUTHOR
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.)