OFFSET
1,1
COMMENTS
See the discussion at A192580.
MATHEMATICA
start = {2, 4, 6, 8}; 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] (* A192583 *)
PrimePi[t] (* A192530 Nonprimes 4, 6, 8 are represented by "next prime down". *)
CROSSREFS
KEYWORD
nonn,fini,full
AUTHOR
Clark Kimberling, Jul 04 2011
STATUS
approved