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Numbers not divisible by any prime of the form 3*k - 1.
0

%I #7 Sep 13 2023 22:50:27

%S 1,3,7,9,13,19,21,27,31,37,39,43,49,57,61,63,67,73,79,81,91,93,97,103,

%T 109,111,117,127,129,133,139,147,151,157,163,169,171,181,183,189,193,

%U 199,201,211,217,219,223,229,237,241,243,247,259,271,273,277,279

%N Numbers not divisible by any prime of the form 3*k - 1.

%C The sequence is closed under multiplication.

%t s = Select[Prime[Range[100]], Mod[#, 3] == 2 &] (* A003627 *)

%t Select[r = Range[Max[s]], Intersection[#/s, r] == {} &]

%Y Cf. A003627, A364832.

%Y A215800 is a subsequence.

%K nonn

%O 1,2

%A _Clark Kimberling_, Aug 09 2023