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 A122108 #4 Feb 04 2015 15:26:22
%S A122108 1,4,8,12,20,24,44,28,52,56,104,56,104,112,212,60,116,120,232,120,232,
%T A122108 240,464,120,232,240,464,240,464,480,932,124,244,248,488,248,488,496,
%U A122108 976,248,488,496,976,496,976,992,1952,248,488,496,976,496,976,992,1952
%N A122108 a(n)=number of 1's ("live" cells) at stage n of a 2-dimensional cellular automaton evolving by the rule: 1 if N+S+E+W is 1 or 2, else 0, starting from a single live cell.
%H A122108 <a href="/index/Ce#cell">Index entries for sequences related to cellular automata</a>
%Y A122108 Cf. A048883.
%K A122108 nonn
%O A122108 1,2
%A A122108 _John W. Layman_, Oct 18 2006