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A192598 Monotonic ordering of set S generated by these rules:  if x and y are in S and x^2+2y^2 is a prime, then x^2+2y^2 is in S, and 1 is in S. 3
1, 3, 11, 19, 139, 251, 379 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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.

LINKS

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

MATHEMATICA

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 *)

CROSSREFS

Cf. A192476, A192580, A192612, A192613.

Sequence in context: A196174 A192591 A075226 * A028978 A082628 A279257

Adjacent sequences:  A192595 A192596 A192597 * A192599 A192600 A192601

KEYWORD

nonn,fini,full

AUTHOR

Clark Kimberling, Jul 05 2011

STATUS

approved

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Last modified February 22 19:47 EST 2019. Contains 320403 sequences. (Running on oeis4.)