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 A239541 #6 Jul 23 2025 11:00:51 %S A239541 405,7790,984150,71388971,5988724293,482858009716,39351464058085, %T A239541 3197707959464813,260051519640219195,21143995321557570468, %U A239541 1719253480434235036170,139793164967480337703364 %N A239541 Number of (7+1)X(n+1) 0..2 arrays with no element equal to all horizontal neighbors or unequal to all vertical neighbors, and new values 0..2 introduced in row major order. %C A239541 Row 7 of A239537 %H A239541 R. H. Hardin, <a href="/A239541/b239541.txt">Table of n, a(n) for n = 1..204</a> %e A239541 Some solutions for n=2 %e A239541 ..0..1..0....0..1..2....0..1..0....0..1..2....0..1..0....0..1..2....0..1..2 %e A239541 ..0..1..0....0..1..2....0..1..0....0..1..2....0..1..0....0..1..2....0..1..2 %e A239541 ..1..0..2....1..2..0....0..1..0....0..1..0....0..1..0....0..1..2....0..1..2 %e A239541 ..1..0..2....1..2..0....0..2..1....0..1..0....0..2..0....2..1..2....2..1..0 %e A239541 ..1..2..0....1..2..1....1..2..1....2..1..0....1..2..0....2..0..2....2..1..0 %e A239541 ..0..2..0....2..0..1....1..2..1....2..1..0....1..2..1....2..0..2....2..1..0 %e A239541 ..0..2..0....2..0..2....0..2..0....1..2..1....1..2..1....0..1..2....1..0..1 %e A239541 ..0..2..0....2..0..2....0..2..0....1..2..1....1..2..1....0..1..2....1..0..1 %K A239541 nonn %O A239541 1,1 %A A239541 _R. H. Hardin_, Mar 21 2014