1,2

See the discussions at A192476 and A192580. The start-set for A192598 is {1}. For results using start-sets {1,2}, and {1,2,4}, see A192612 and A192613.

Table of n, a(n) for n=1..7.

start = {1}; primes = Table[Prime[n], {n, 1, 20000}];

f[x_, y_] := If[MemberQ[primes, x^2 + 2 y^2], x^2 + 2 y^2]

b[x_] :=

Block[{w = x},

Select[Union[

Flatten[AppendTo[w,

Table[f[w[[i]], w[[j]]], {i, 1, Length[w]}, {j, 1,

Length[w]}]]]], # < 30000 &]];

t = FixedPoint[b, start] (* A192598 *)

Cf. A192476, A192580, A192612, A192613.

Sequence in context: A196174 A192591 A075226 * A028978 A082628 A279257

Adjacent sequences: A192595 A192596 A192597 * A192599 A192600 A192601

nonn,fini,full

Clark Kimberling, Jul 05 2011

approved