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.

2, 3, 4, 5, 7, 11, 13, 19, 37, 43, 73

Offset

1,1

Comments

See the discussions at A192476 and A192580.

Links

Table of n, a(n) for n=1..11.

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]  (* A192586 *)

Crossrefs

Cf. A192476, A192580, A192587, A192588.

Sequence in context: A073019 A174291 A007885 * A003037 A347983 A259466

Adjacent sequences: A192583 A192584 A192585 * A192587 A192588 A192589

Keyword

nonn,fini,full

Author

Clark Kimberling, Jul 05 2011

Status

approved