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 A166493 #10 Mar 11 2022 08:02:32
%S A166493 1,1,1,2,3,3,4,5,5,6,6,6,8,8,8,10,9,10,1,7,15,12,11,14,14,12,16,16,16,
%T A166493 16,16,20,17,17,20,11,21,25,18,20,26,22,24,19,27,17,23,30,13,28,36,24,
%U A166493 25,32,27,30,32,28,32,36,30,32,3,50,40,22,43,31,37,35,28,40,44,33,38,49
%N A166493 A Per Bak sand pile collapse sequence using Hofstadter Q:A005185, of the A153112 form.
%t A166493 f[0] = 1; f[1] = 1; f[2] = 1;
%t A166493 f[n_] := f[n] = If[Mod[Floor[Sum[f[i], {i, 0, n - 1}]/2], 2^(4 + Mod[n, 3])] == 0, 1 + Mod[n, 3], f[n - f[n - 1]] + f[n - f[n - 2]]];
%t A166493 a = Table[f[n], {n, 0, 200}]
%Y A166493 Cf. A153112, A005185.
%K A166493 nonn,uned
%O A166493 0,4
%A A166493 _Roger L. Bagula_, Oct 15 2009