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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

%I

%S 1,7,19,37,43,73,79,97,109,151,163,181,193,199,223,229,241,271,307,

%T 313,331,337,367,373,379,397,409,421,433,439,457,463,487,499,523,541,

%U 547,571,577,601,613,619,631,643,661,673,691,709,727,739,751,757,769

%N 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.

%C See the discussions at A192476 and A192580.

%t start = {1}; primes = Table[Prime[n], {n, 1, 1000}];

%t f[x_, y_] := If[MemberQ[primes, 5 x + 2 y], 5 x + 2 y]

%t b[x_] :=

%t Block[{w = x},

%t Select[Union[

%t Flatten[AppendTo[w,

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

%t Length[w]}]]]], # < 2000 &]];

%t t = FixedPoint[b, start] (* A192594 *)

%t PrimePi[t] (* A192595 *)

%Y Cf. A192595, A192476, A192580.

%K nonn

%O 1,2

%A _Clark Kimberling_, Jul 05 2011

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Last modified February 5 23:07 EST 2023. Contains 360091 sequences. (Running on oeis4.)