A141096 - OEIS

%I #15 Sep 30 2024 04:49:56

%S 4,6,8,12,14,18,20,24,30,32,38,42,48,54,60,72,80,84,90,108,110,132,

%T 138,140,150,180

%N Even numbers not representable as the sum of two coprime nonprime numbers.

%C Numbers k such that A141095(k/2) = 0.

%C 180 is the last term.

%C This sequence is a subsequence of A141098.

%t t = Table[Length[Select[Range[n/2], ! PrimeQ[#] && ! PrimeQ[n - #] && GCD[#, n - #] == 1 &]], {n, 2, 2000, 2}]; Flatten[2*Position[t, 0]] (* _T. D. Noe_, Dec 05 2013 *)

%Y Cf. A141095, A141098.

%K nonn,fini,full,changed

%O 1,1

%A _T. D. Noe_, Jun 02 2008