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 A228384 #9 Dec 18 2015 18:18:38 %S A228384 1,2,21,382,17578,1755243,402968942,207573951234,242284444195349, %T A228384 638096588519781536,3798652903378388363280,51076133156779686951912785, %U A228384 1551660182965034835583479000348,106488245934766828340647881986248382 %N A228384 Number of n X n binary arrays with top left value 1 and no two ones adjacent horizontally or vertically. %C A228384 Diagonal of A228390 %H A228384 R. H. Hardin, <a href="/A228384/b228384.txt">Table of n, a(n) for n = 1..30</a> %e A228384 Some solutions for n=4 %e A228384 ..1..0..0..0....1..0..0..1....1..0..1..0....1..0..0..1....1..0..0..0 %e A228384 ..0..0..0..1....0..0..1..0....0..1..0..0....0..0..0..0....0..0..1..0 %e A228384 ..0..0..1..0....0..0..0..0....0..0..0..1....1..0..1..0....1..0..0..1 %e A228384 ..0..0..0..1....0..1..0..0....0..1..0..0....0..1..0..1....0..0..1..0 %K A228384 nonn %O A228384 1,2 %A A228384 _R. H. Hardin_ Aug 21 2013