1,1

See the discussions at A192476 and A192580.

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

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 *)

Cf. A192476, A192580, A192587, A192588.

Sequence in context: A073019 A174291 A007885 * A003037 A347983 A259466

Adjacent sequences: A192583 A192584 A192585 * A192587 A192588 A192589

nonn,fini,full

Clark Kimberling, Jul 05 2011

approved