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 A167679 #4 Mar 31 2017 20:35:15
%S A167679 1,2,1,2,1,2,1,2,1,2,21,22,21,22,21,22,21,22,21,22,11,12,11,12,11,12,
%T A167679 11,12,11,12,21,22,21,22,21,22,21,22,21,22,11,12,11,12,11,12,11,12,11,
%U A167679 12,21,22,21,22,21,22,21,22,21,22,11,12,11,12,11,12,11,12,11,12,21,22,21
%N A167679 Replace odd digits with 2 and even digits with 1.
%t A167679 Table[FromDigits[If[OddQ[ # ],2,1]&/@IntegerDigits[n]],{n,0,200}]
%Y A167679 Cf. A065031, A167677, A167678.
%K A167679 base,nonn
%O A167679 0,2
%A A167679 _Zak Seidov_, Nov 09 2009