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 A209516 #8 Oct 06 2015 21:47:45 %S A209516 3813753,2505266673,1701725703867,1170258116647953,808953988260058047, %T A209516 560493388203596285283,388756746462464273412765, %U A209516 269773510833311326186049823,187249435580728303988081172345 %N A209516 Number of (n+1) X 8 0..2 arrays with the number of clockwise edge increases in every 2 X 2 subblock equal to the number of counterclockwise edge increases. %C A209516 Column 7 of A209517. %H A209516 R. H. Hardin, <a href="/A209516/b209516.txt">Table of n, a(n) for n = 1..210</a> %e A209516 Some solutions for n=4: %e A209516 ..2..1..0..2..1..2..2..1....2..2..2..2..1..0..2..0....2..0..1..2..2..1..1..1 %e A209516 ..1..0..1..0..2..0..2..1....1..2..2..1..1..0..2..2....1..2..0..1..2..2..1..1 %e A209516 ..0..2..0..0..0..1..0..2....0..1..1..2..2..1..0..2....0..1..2..0..1..2..2..1 %e A209516 ..1..0..2..0..0..1..1..0....1..0..0..1..1..0..2..1....2..0..1..2..0..1..1..0 %e A209516 ..0..1..0..1..0..0..0..0....0..1..0..0..0..0..2..1....1..2..0..1..2..0..0..2 %K A209516 nonn %O A209516 1,1 %A A209516 _R. H. Hardin_, Mar 09 2012