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A192594
Monotonic ordering of set S generated by these rules: if x and y are in S and 5x+2y is a prime, then 5x+2y is in S, and 1 is in S.
2
1, 7, 19, 37, 43, 73, 79, 97, 109, 151, 163, 181, 193, 199, 223, 229, 241, 271, 307, 313, 331, 337, 367, 373, 379, 397, 409, 421, 433, 439, 457, 463, 487, 499, 523, 541, 547, 571, 577, 601, 613, 619, 631, 643, 661, 673, 691, 709, 727, 739, 751, 757, 769
OFFSET
1,2
COMMENTS
See the discussions at A192476 and A192580.
MATHEMATICA
start = {1}; primes = Table[Prime[n], {n, 1, 1000}];
f[x_, y_] := If[MemberQ[primes, 5 x + 2 y], 5 x + 2 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]}]]]], # < 2000 &]];
t = FixedPoint[b, start] (* A192594 *)
PrimePi[t] (* A192595 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Jul 05 2011
STATUS
approved