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 A241277 #7 Jun 02 2025 10:03:02 %S A241277 2,3,41,773,20717,15616828,2949336562 %N A241277 Number of n X n 0..3 arrays with no element equal to one plus the sum of elements to its left or zero plus the sum of the elements above it or one plus the sum of the elements diagonally to its northwest or one plus the sum of the elements antidiagonally to its northeast, modulo 4. %C A241277 Diagonal of A241283 %e A241277 Some solutions for n=4 %e A241277 ..3..3..2..3....3..2..3..3....3..3..2..3....3..2..3..3....3..2..3..3 %e A241277 ..2..1..3..2....2..1..1..2....2..1..3..2....2..1..1..2....0..3..1..2 %e A241277 ..2..2..2..0....2..0..2..3....3..2..0..0....0..2..2..2....2..0..1..3 %e A241277 ..2..0..0..0....2..0..1..2....2..1..2..3....2..2..0..0....0..2..2..2 %K A241277 nonn %O A241277 1,1 %A A241277 _R. H. Hardin_, Apr 18 2014