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.
Original entry on oeis.org
1, 3, 11, 19, 139, 251, 379
Offset: 1
-
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 *)
A192613
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, 2, and 4 are in S.
Original entry on oeis.org
1, 2, 3, 4, 11, 17, 19, 41, 139, 251, 307, 379, 587, 1699, 3371
Offset: 1
-
start = {1, 2, 4}; 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] (* A192613 *)
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