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A192596
Monotonic ordering of set S generated by these rules: if x and y are in S and 3x+4y is a prime, then 3x+4y is in S, and 1 is in S.
2
1, 7, 31, 97, 127, 409, 601, 769, 1231, 1657, 1831, 2017, 2311, 3079, 3169, 3457, 3631, 3697, 3943, 4201, 4999, 5479, 5521, 5881, 6079, 6151, 6607, 6961, 7057, 7129, 7321, 7417, 7687, 8089, 8161, 8431, 9127, 9241, 9337, 9511, 9631, 9871, 10009
OFFSET
1,2
COMMENTS
See the discussions at A192476 and A192580.
MATHEMATICA
start = {1}; primes = Table[Prime[n], {n, 1, 10000}];
f[x_, y_] := If[MemberQ[primes, 3 x + 4 y], 3 x + 4 y]
b[x_] :=
Block[{w = x},
Select[Union[
Flatten[AppendTo[w,
Table[f[w[[i]], w[[j]]], {i, 1, Length[w]}, {j, 1,
Length[w]}]]]], # < 20000 &]];
t = FixedPoint[b, start] (* A192596 *)
PrimePi[t] (* A192597 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Jul 05 2011
STATUS
approved