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 A233076 #8 Jun 19 2025 20:50:19 %S A233076 1,14,1985,1588262,6938214854,165407945648306,21520525142517911969, %T A233076 15280137439726087042287674,59207172638901578439239726940974, %U A233076 1251961921151721201415260511387809535370 %N A233076 Number of n X n 0..3 arrays with no element x(i,j) adjacent to value 3-x(i,j) horizontally or antidiagonally, top left element zero, and 1 appearing before 2 in row major order. %C A233076 Diagonal of A233082. %H A233076 R. H. Hardin, <a href="/A233076/b233076.txt">Table of n, a(n) for n = 1..13</a> %e A233076 Some solutions for n=3 %e A233076 ..0..0..0....0..1..1....0..1..3....0..0..0....0..1..3....0..1..1....0..0..1 %e A233076 ..1..0..0....1..3..1....3..2..0....0..0..1....1..3..2....1..1..0....0..0..0 %e A233076 ..0..0..2....2..3..1....3..2..2....1..1..0....2..3..3....0..2..2....0..1..1 %Y A233076 Cf. A233082. %K A233076 nonn %O A233076 1,2 %A A233076 _R. H. Hardin_, Dec 03 2013