A192582 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, 4, and 6 are in S.

2, 4, 5, 6, 11, 13, 17, 23, 31, 37, 47, 53, 67, 79, 103, 107, 139, 149, 223, 269, 283, 317, 557, 619, 643, 1699, 2477, 3343

Offset

1,1

Comments

See the discussion at A192580.

Links

Table of n, a(n) for n=1..28.

Mathematica

start = {2, 4, 6}; 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}]]]], # <
      10000000 &]];
t = FixedPoint[b, start]  (* A192582 *)

Crossrefs

Cf. A192476.

Sequence in context: A278507 A113631 A202101 * A101951 A171166 A194607

Adjacent sequences: A192579 A192580 A192581 * A192583 A192584 A192585

Keyword

nonn,fini,full

Author

Clark Kimberling, Jul 04 2011

Status

approved