OFFSET
1,1
COMMENTS
See A192645.
LINKS
Ivan Neretin, Table of n, a(n) for n = 1..10000
MATHEMATICA
start = {2, 3};
f[x_, y_] := If[MemberQ[Range[1, 150000], x^2 - y^2], x^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, i}]]]], # <
150000 &]];
t = FixedPoint[b, start] (* A192648 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Jul 06 2011
STATUS
approved