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 A103957 #15 Dec 18 2022 07:03:46
%S A103957 1,1,2,1,1,2,1,1,2,1,2,1,2,1,3,1,1,2,1,2,1,2,1,3,1,2,1,2,1,3,1,2,1,3,
%T A103957 1,2,1,3,1,2,1,1,1,2,1,2,1,2,1,3,1,2,1,2,1,3,1,2,1,3,1,2,1,3,1,2,1,1,
%U A103957 1,2,1,2,1,2,1,3,1,2,1,2,1,3,1,2,1,3,1,2,1,3,1,2,1,1,2,1,2,1,3,1,2,1,3,1,2
%N A103957 A nonsense sequence.
%F A103957 Involves substitutions 1-> {1, 2}, 2->{1, 3}, 3->1.
%t A103957 Hofstadter[n_Integer? Positive] := Hofstadter[n] = Hofstadter[n - Hofstadter[n - 1]] + Hofstadter[n - Hofstadter[n - 2]];
%t A103957 Hofstadter[0] = Hofstadter[1] = 1;
%t A103957 s[1] = {1, 2}; s[2] = {1, 3}; s[3] = {1};
%t A103957 t[a_] := Join[a, Flatten[s /@ a]];
%t A103957 p[0] = {1}; p[1] = t[{1}];
%t A103957 p[n_] := t[p[n - 1]];
%t A103957 Flatten[Table[p[If[n > 0, Hofstadter[n], n]], {n, 0, 7}]]
%Y A103957 Cf. A073058, A103684.
%K A103957 nonn,uned,less
%O A103957 0,3
%A A103957 _Roger L. Bagula_, Mar 30 2005