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 A241253 #5 Jun 02 2025 10:02:11 %S A241253 15,22,135,1202,11700,124372,1558957,22016913,362503120,6317232175, %T A241253 119650082800 %N A241253 Number of nX6 0..3 arrays with no element equal to one plus the sum of elements to its left or zero plus the sum of elements above it or one plus the sum of the elements diagonally to its northwest or zero plus the sum of the elements antidiagonally to its northeast, modulo 4. %C A241253 Column 6 of A241255 %e A241253 Some solutions for n=4 %e A241253 ..3..3..2..3..3..2....3..3..2..2..2..3....3..3..2..2..2..3....3..3..2..2..2..3 %e A241253 ..2..1..1..2..1..1....2..1..1..0..0..2....2..1..3..0..1..1....2..1..3..0..1..1 %e A241253 ..2..2..2..2..2..2....0..2..0..0..0..2....0..2..0..1..2..1....0..2..0..1..2..1 %e A241253 ..0..0..2..0..0..2....2..0..2..0..0..2....0..0..0..2..2..2....2..0..0..2..2..2 %K A241253 nonn %O A241253 1,1 %A A241253 _R. H. Hardin_, Apr 18 2014