%I
%S 2,3,4,5,7,11,13,19,37,43,73
%N Monotonic ordering of set S generated by these rules: if x and y are in S and xy1 is a prime, then xy1 is in S, and 2 and 4 are in S.
%C See the discussions at A192476 and A192580.
%t start = {2, 4}; primes = Table[Prime[n], {n, 1, 10000}];
%t f[x_, y_] := If[MemberQ[primes, x*y  1], x*y  1]
%t b[x_] :=
%t Block[{w = x},
%t Select[Union[
%t Flatten[AppendTo[w,
%t Table[f[w[[i]], w[[j]]], {i, 1, Length[w]}, {j, 1, i}]]]], # <
%t 50000 &]];
%t t = FixedPoint[b, start] (* A192586 *)
%Y Cf. A192476, A192580, A192587, A192588.
%K nonn,fini,full
%O 1,1
%A _Clark Kimberling_, Jul 05 2011
