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 A097981 #13 Feb 18 2015 07:53:46 %S A097981 4,8,12,16,24,32,52,40,56,72,72,92,128,140,136,160,152,200,244,236, %T A097981 264,232,268,360,316,416,320,384,436,412,500,492,500,524,680,584,744, %U A097981 700,764,884,896,748,1056,864,888,992,1036,1060,1296,1268,1436,1408,1472 %N A097981 Cell populations in the development of the 2 X 2 square with the 2D cellular automaton rule seeds (/2). %H A097981 Eric M. Schmidt, <a href="/A097981/b097981.txt">Table of n, a(n) for n = 0..1000</a> %H A097981 Eric M. Schmidt, <a href="/A097981/a097981.cpp.txt">C++ code to compute this sequence</a> %H A097981 Mirek Wojtowicz, <a href="http://www.mirekw.com/ca/">Information on many 2D cellular automata</a> %H A097981 <a href="/index/Ce#cell">Index entries for sequences related to cellular automata</a> %e A097981 a(0) = 4 because the 2 X 2 square contains 4 cells. a(1) = 8 because 8 cells are neighbors of exactly 2 of the original 4 cells. a(2) = 12 because 12 cells are neighbors of exactly 2 of the previous 8 cells. %Y A097981 Cf. A097995, A097996. %K A097981 nonn %O A097981 0,1 %A A097981 _Oliver Pechenik_, Sep 07 2004 %E A097981 Offset changed by _Eric M. Schmidt_, Mar 10 2013