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%I #16 Sep 30 2024 18:40:30
%S 40,48,62,68,72,82,96,100,108,114,138,142,158,172,176,178,184,194,208,
%T 212,222,232,238,260,264,268,272,278,282,290,298,300,308,320,334,342,
%U 348,352,358,360,378,380,382,386,392,402,414,418,422,424,438,444,446,448,450
%N Even numbers k such that 3*k-1 and 3*k+1 are not prime.
%H Robert Israel, <a href="/A120382/b120382.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = 2*A060461(n). - _Michel Marcus_, Sep 15 2019
%p remove(k -> isprime(3*k-1) or isprime(3*k+1), [seq(k,k=2..1000,2)]); # _Robert Israel_, Sep 30 2024
%t Select[Range[2,450,2],!PrimeQ[3#-1]&&!PrimeQ[3#+1]&] (* _James C. McMahon_, Sep 30 2024 *)
%o (PARI) isok(n) = !(n%2) && !isprime(3*n-1) && !isprime(3*n+1); \\ _Michel Marcus_, Sep 15 2019
%Y Cf. A060461.
%K easy,nonn
%O 1,1
%A _Pierre CAMI_, Jun 29 2006
%E More terms from _Michel Marcus_, Sep 15 2019