A167692 - OEIS

%I #12 Nov 10 2024 16:08:26

%S 0,8,10,14,16,20,22,24,26,28,32,34,36,38,40,44,46,48,50,52,54,56,58,

%T 62,64,66,68,70,74,76,78,80,82,84,86,88,90,92,94,96,98,100,104,106,

%U 110,112,114,116,118,120,122,124,126,128,130,132,134,136,140,142,144,146,148

%N The even nonisolated nonprimes.

%C Zero together with A100319, the even numbers n such that at least one of n-1 and n+1 is composite.

%H G. C. Greubel, <a href="/A167692/b167692.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Range[0, 100], Mod[#, 2] == 0 && !PrimeQ[#] && (! PrimeQ[# - 1] || !PrimeQ[# + 1]) &] (* _G. C. Greubel_, Jul 07 2016 *)

%t Join[{0},Select[Range[2,150,2],AnyTrue[#+{1,-1},CompositeQ]&]] (* _Harvey P. Dale_, Nov 10 2024 *)

%o (PARI) isA167692(n) = (n%2==0)&&!isprime(n)&&(!isprime(n-1)||!isprime(n+1)) \\ _Michael B. Porter_, Feb 02 2010

%Y Cf. A100319, A164276.

%K nonn,easy,less

%O 1,2

%A _Juri-Stepan Gerasimov_, Nov 09 2009

%E Edited by _Charles R Greathouse IV_, Mar 22 2010