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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
2, 4, 5, 11, 17, 23, 47
OFFSET
1,1
COMMENTS
See the discussion at A192580. As sets, A192580 lies in A192581, which lies in A192582.
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 *)
CROSSREFS
Sequence in context: A089416 A056817 A352255 * A095023 A049913 A223220
KEYWORD
nonn,fini,full
AUTHOR
Clark Kimberling, Jul 04 2011
STATUS
approved