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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

See the discussions at A192476 and A192580.

LINKS

Table of n, a(n) for n=1..5.

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

Cf. A192476, A192580.

Sequence in context: A088733 A128996 A196174 * A075226 A192598 A028978

Adjacent sequences:  A192588 A192589 A192590 * A192592 A192593 A192594

KEYWORD

nonn,fini,full

AUTHOR

Clark Kimberling, Jul 05 2011

STATUS

approved

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Last modified August 9 18:55 EDT 2022. Contains 356026 sequences. (Running on oeis4.)