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 A140314 #13 Dec 06 2024 04:05:00 %S A140314 1,2,11,195,8969,1232795,471487297,516844071813,1603508113421239, %T A140314 14148460147460008963,354360105981877906958557, %U A140314 25210728065407321182797745205,5093486498660018140333056634922039 %N A140314 Number of n X n binary matrices containing no more than two 1's in any 2 X 2 subblock. %C A140314 No more than 1 1 in any 2 X 2 subblock gives A063443. %C A140314 No more than 3 1's in any 2 X 2 subblock gives A139810. %H A140314 R. H. Hardin, May 25 2008, <a href="/A140314/b140314.txt">Table of n, a(n) for n = 0..15</a> %Y A140314 Cf. A063443, A139810. %K A140314 nonn %O A140314 0,2 %A A140314 _R. H. Hardin_, May 25 2008