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 A233725 #6 Jul 23 2025 08:10:10 %S A233725 40,756,29816,2723072,578163016,297173770244,365411698279744, %T A233725 1098248392267801764,7928574480658025834472, %U A233725 139889299008340046298542520 %N A233725 Number of (n+1)X(n+1) 0..3 arrays with every 2X2 subblock having the sum of the absolute values of the edge differences equal to 6 and no adjacent elements equal. %C A233725 Diagonal of A233733 %e A233725 Some solutions for n=3 %e A233725 ..1..3..2..3....3..1..3..2....0..1..3..1....0..1..3..2....2..0..2..0 %e A233725 ..0..1..0..1....2..0..1..3....2..0..2..0....2..0..2..0....3..2..3..2 %e A233725 ..3..2..3..2....3..1..3..2....3..1..3..1....3..1..3..1....2..0..2..0 %e A233725 ..0..1..0..1....1..0..1..0....1..0..2..3....1..0..2..0....0..1..0..1 %K A233725 nonn %O A233725 1,1 %A A233725 _R. H. Hardin_, Dec 15 2013