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
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
KEYWORD
nonn,easy
AUTHOR
Juri-Stepan Gerasimov, Aug 11 2009
EXTENSIONS
40 added by R. J. Mathar, Aug 27 2009
STATUS
approved