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 A140307 #4 Mar 31 2012 12:35:07 %S A140307 1,2,16,256,15982,3082378,1476568000,2280441045555,10599616558936358, %T A140307 140380164790852384033 %N A140307 Number of n X n binary matrices containing at most four 1's in any 3 X 3 sub-block. %Y A140307 Cf. A139810. %K A140307 nonn %O A140307 0,2 %A A140307 _R. H. Hardin_, May 27 2008