A192590 Monotonic ordering of set S generated by these rules: if x and y are in S and xy-3 is a prime, then xy-3 is in S, and 2 and 4 are in S.

2, 4, 5, 7, 11, 13, 17, 19, 23, 31, 41, 43, 59, 73, 79, 83, 89, 163, 233, 313, 353, 463, 929, 1249, 1409, 4993

Offset

1,1

Comments

See the discussions at A192476 and A192580.

Links

Table of n, a(n) for n=1..26.

Mathematica

start = {2, 4}; primes = Table[Prime[n], {n, 1, 40000}];
f[x_, y_] := If[MemberQ[primes, x*y - 3], x*y - 3]
b[x_] :=
  Block[{w = x},
   Select[Union[
     Flatten[AppendTo[w,
       Table[f[w[[i]], w[[j]]], {i, 1, Length[w]}, {j, 1, i}]]]], # <
      200000 &]];
t = FixedPoint[b, start]    (* A192590 *)

Crossrefs

Cf. A192476, A192580.

Sequence in context: A350147 A110924 A335402 * A028289 A307872 A239510

Adjacent sequences: A192587 A192588 A192589 * A192591 A192592 A192593

Keyword

nonn,fini,full

Author

Clark Kimberling, Jul 05 2011

Status

approved