A192581 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.

2, 4, 5, 11, 17, 23, 47

Offset: 1

Author

Clark Kimberling, Jul 04 2011

Keywords

• nonn
• fini
• full

Comments

See the discussion at A192580. As sets, A192580 lies in A192581, which lies in A192582.

Crossrefs

Cf. A192476, A192580.

Programs

Mathematica

start = {2, 4}; primes = Table[Prime[n], {n, 1, 10000}];
f[x_, y_] := If[MemberQ[primes, x*y + 1], x*y + 1]
b[x_] :=
  Block[{w = x},
   Select[Union[
     Flatten[AppendTo[w,
       Table[f[w[[i]], w[[j]]], {i, 1, Length[w]}, {j, 1, i}]]]], # <
      50000 &]];
t = FixedPoint[b, start]  (* A192581 *)