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 A090193 #15 Mar 15 2015 18:32:48
%S A090193 1,2,0,2,0,1,0,1,2,2,0,1,0,1,2,1,2,0,0,1,2,1,2,0,2,0,1,2,0,1,0,1,2,1,
%T A090193 2,0,0,1,2,1,2,0,2,0,1,1,2,0,2,0,1,0,1,2,0,1,2,1,2,0,2,0,1,1,2,0,2,0,
%U A090193 1,0,1,2,2,0,1,0,1,2,1,2,0,2,0,1,0,1,2,1,2,0,0,1,2,1,2,0,2,0,1,1,2,0,2,0,1
%N A090193 a(n) = A053838(n) + 1 modulo 3.
%C A090193 Can construct sequence by starting with 1 and mapping 0->012, 1->120, 2->201 (e.g. 1, 120, 120201012, ...) and looking at n-th digit of a term with sufficient digits.
%H A090193 Vincenzo Librandi, <a href="/A090193/b090193.txt">Table of n, a(n) for n = 0..2000</a>
%t A090193 Mod[ Nest[ Join[ #, # + 1, # + 2] &, {1}, 5], 3] (* _Robert G. Wilson v_, Jul 27 2014 *)
%K A090193 base,nonn
%O A090193 0,2
%A A090193 _Philippe Deléham_, Feb 04 2004