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 A240186 #7 Jun 09 2023 21:43:50 %S A240186 1,5,37,771,91879,28061567,43398047802 %N A240186 Number of n X n 0..3 arrays with no element equal to zero plus the sum of elements to its left or one plus the sum of the elements above it or three plus the sum of the elements diagonally to its northwest, modulo 4. %C A240186 Diagonal of A240192. %e A240186 Some solutions for n=4 %e A240186 ..2..0..0..0....2..0..0..0....2..0..0..0....2..0..0..0....2..0..0..0 %e A240186 ..1..2..0..2....1..3..2..0....1..0..0..0....1..0..2..2....1..3..2..0 %e A240186 ..2..1..0..2....2..1..1..3....1..3..3..0....1..2..2..2....2..1..2..0 %e A240186 ..1..2..0..2....1..0..3..2....2..1..2..2....2..1..0..0....1..2..2..0 %Y A240186 Cf. A240192. %K A240186 nonn %O A240186 1,2 %A A240186 _R. H. Hardin_, Apr 02 2014