This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A131852 #11 Mar 03 2019 03:44:49
%S A131852 0,0,1,1,0,0,1,1,-1,-1,0,0,-1,-1,0,0,0,0,1,1,0,0,1,1,-1,-1,0,0,-1,-1,
%T A131852 0,0,1,1,2,2,1,1,2,2,0,0,1,1,0,0,1,1,1,1,2,2,1,1,2,2,0,0,1,1,0,0,1,1,
%U A131852 0,0,1,1,0,0,1,1,-1,-1,0,0,-1,-1,0,0,0,0,1,1,0,0,1,1,-1,-1,0,0,-1,-1,0,0,1,1,2,2,1,1,2,2,0,0,1,1,0,0,1,1,1,1,2,2,1,1,2,2,0
%N A131852 Imaginary part of the function z defined in A131851.
%C A131852 a(A000079(n)) = A056594(n+3);
%C A131852 a(A131855(n)) = 0; a(A131862(n)) > 0; a(A131857(n)) = 1; a(A131864(n)) < 0;
%C A131852 for n > 0: a(A098704(n+1)) = n and abs(a(m)) < n for m < A098704(n+1).
%H A131852 R. Zumkeller, <a href="/A131852/b131852.txt">Table of n, a(n) for n = 0..10000</a>
%t A131852 z[0] = 0; z[n_] := z[n] = z[Floor[n/2]]*I + Mod[n, 2]; Table[z[n] // Im, {n, 0, 120}] (* _Jean-François Alcover_, Mar 02 2019 *)
%K A131852 sign
%O A131852 0,35
%A A131852 _Reinhard Zumkeller_, Jul 22 2007