[go: up one dir, main page]

login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Difference sequence of A256793.
2

%I #6 Apr 14 2015 11:05:12

%S 1,2,3,2,2,3,3,1,2,3,3,2,1,2,3,3,2,2,1,2,3,2,1,2,2,2,1,2,3,2,2,1,2,2,

%T 2,1,2,3,3,1,2,1,2,2,2,1,2,3,2,3,1,2,1,2,2,2,1,2,3,2,2,3,1,2,1,2,2,2,

%U 1,2,3,3,1,2,3,1,2,1,2,2,2,1,2,3,2,1

%N Difference sequence of A256793.

%C These are the numbers of consecutive positive traces when the minimal alternating squares representations for positive integers are written in order. Is every term < 5? The first term greater than 3 is a(116) = 4, corresponding to these 3 consecutive representations:

%C R(225) = 225;

%C R(226) = 256 - 36 + 9 - 4 + 1;

%C R(227) = 256 - 36 + 9 - 4 + 2.

%C (See A256789 for definitions.)

%t b[n_] := n^2; bb = Table[b[n], {n, 0, 1000}]; (* Squares as base *)

%t s[n_] := Table[b[n], {k, 1, 2 n - 1}];

%t h[1] = {1}; h[n_] := Join[h[n - 1], s[n]];

%t g = h[100]; r[0] = {0}; r[1] = {1}; r[2] = {4, -2};

%t r[n_] := If[MemberQ[bb, n], {n}, Join[{g[[n]]}, -r[g[[n]] - n]]];

%t Table[r[n], {n, 0, 120}]; (* A256789 *)

%t u = Flatten[Table[Last[r[n]], {n, 1, 1000}]]; (* A256791 *)

%t u1 = Select[Range[800], u[[#]] > 0 &]; (* A256792 *)

%t u2 = Select[Range[800], u[[#]] < 0 &]; (* A256793 *)

%t Differences[u1] (* A256794 *)

%t Differences[u2] (* A256795 *)

%Y Cf. A256792, A256794.

%K nonn,easy

%O 1,2

%A _Clark Kimberling_, Apr 13 2015