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 A280672 #4 Jan 07 2017 08:06:45 %S A280672 224,61880,16438612,4460317695,1208240638772,327452072560351, %T A280672 88741877287328326,24049810737844448684,6517703746847251930646, %U A280672 1766353341829714295007100,478696830022637290656991583 %N A280672 Number of nX7 0..2 arrays with no element equal to more than one of its horizontal and antidiagonal neighbors and with new values introduced in order 0 sequentially upwards. %C A280672 Column 7 of A280673. %H A280672 R. H. Hardin, <a href="/A280672/b280672.txt">Table of n, a(n) for n = 1..27</a> %e A280672 Some solutions for n=2 %e A280672 ..0..0..1..1..0..0..1. .0..1..0..1..0..1..2. .0..1..0..1..0..2..2 %e A280672 ..2..2..0..2..2..1..2. .2..2..1..2..1..2..1. .1..2..1..2..0..0..2 %Y A280672 Cf. A280673. %K A280672 nonn %O A280672 1,1 %A A280672 _R. H. Hardin_, Jan 07 2017