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A192586 Monotonic ordering of set S generated by these rules:  if x and y are in S and xy-1 is a prime, then xy-1 is in S, and 2 and 4 are in S. 3

%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 xy-1 is a prime, then xy-1 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

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Last modified February 25 19:31 EST 2020. Contains 332256 sequences. (Running on oeis4.)