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First differences of A192645.
6

%I #9 Jun 26 2017 01:06:25

%S 1,1,2,3,8,5,3,15,16,5,3,72,50,7,39,16,5,3,65,49,8,39,16,5,3,72,39,16,

%T 5,3,369,1,135,185,192,39,8,8,5,3,1,368,190,369,1,46,89,47,8,130,192,

%U 39,16,5,3,17,118,185,49,48,87,8,39,16,5,3,114,192,39,16,5,3,48

%N First differences of A192645.

%C Does this sequence include 1 infinitely many times?

%e A192645 = (1, 2, 3, 5, 8, 16, 21, ...) gives (2-1, 3-2, 5-3, 8-5, 16-8, 21-16, ...)

%t start = {1, 2};

%t f[x_, y_] := If[MemberQ[Range[1, 5000], x^2 - y^2], x^2 - y^2]

%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, i}]]]], # <

%t 5000 &]];

%t t = FixedPoint[b, start] (* A192645 *)

%t Differences[t] (* A192646 *)

%Y Cf. A192476, A192645.

%K nonn

%O 1,3

%A _Clark Kimberling_, Jul 06 2011