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A298866 Positions of primes p when all p and 4*p are arranged in increasing order.

%I A298866 #6 Apr 17 2018 18:32:22
%S A298866 1,2,3,4,6,8,9,10,12,14,15,16,17,18,20,22,23,24,25,27,28,30,31,32,34,
%T A298866 35,36,37,38,39,42,43,44,45,47,48,49,50,52,54,55,56,58,59,60,61,62,64,
%U A298866 65,66,67,69,70,72,73,74,76,77,78,79,80,83,84,85,86,88
%N A298866 Positions of primes p when all p and 4*p are arranged in increasing order.
%H A298866 Clark Kimberling, <a href="/A298866/b298866.txt">Table of n, a(n) for n = 1..1000</a>
%e A298866 The joint ranking begins with 2,3,5,7,8,11,12,13,17,19,20, as in A298865, so that ranks occupied by primes are 1,2,3,4,6,7,8,10,...
%t A298866 z = 200; u = Prime[Range[z]]; w = Take[Union[u, 4 u], z]; (* A298865 *)
%t A298866 p[n_] := If[MemberQ[u, w[[n]]], 0, 1];
%t A298866 t = Table[p[n], {n, 1, z}];
%t A298866 Flatten[Position[t, 0]]  (* A298866 *)
%t A298866 Flatten[Position[t, 1]]  (* A298867 *)
%Y A298866 Cf. A000040, A298866, A298867 (complement).
%K A298866 nonn,easy
%O A298866 1,2
%A A298866 _Clark Kimberling_, Apr 14 2018