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A192591
Monotonic ordering of set S generated by these rules: if x and y are in S and x^2+y^2+1 is a prime, then x^2+y^2+1 is in S, and 1 is in S.
1
1, 3, 11, 19, 131
OFFSET
1,2
COMMENTS
See the discussions at A192476 and A192580.
MATHEMATICA
start = {1}; primes = Table[Prime[n], {n, 1, 40000}];
f[x_, y_] := If[MemberQ[primes, x^2 + y^2 + 1], x^2 + y^2 + 1]
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] (* A192591 *)
CROSSREFS
Sequence in context: A088733 A128996 A196174 * A075226 A192598 A028978
KEYWORD
nonn,fini,full
AUTHOR
Clark Kimberling, Jul 05 2011
STATUS
approved