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 A240158 #5 Jun 02 2025 09:41:19 %S A240158 15,144,825,22412,108201,1608415,12812998,70360014,694603093, %T A240158 4788445889,30873934965 %N A240158 Number of 6Xn 0..3 arrays with no element equal to one plus the sum of elements to its left or one plus the sum of the 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 A240158 Row 6 of A240153 %e A240158 Some solutions for n=3 %e A240158 ..3..2..3....3..2..3....2..2..3....2..2..3....3..3..2....2..2..3....3..3..2 %e A240158 ..3..2..1....3..1..2....0..2..1....0..2..1....2..1..2....0..2..2....2..1..2 %e A240158 ..2..2..3....2..1..3....2..2..3....2..2..3....0..0..3....0..3..3....0..0..2 %e A240158 ..2..0..1....2..2..3....0..2..2....0..2..1....0..2..1....0..2..2....0..3..1 %e A240158 ..0..0..2....0..2..2....0..0..3....0..2..2....0..2..2....0..3..1....3..3..1 %e A240158 ..2..0..2....0..0..3....3..2..3....2..0..2....0..0..2....0..2..1....3..2..3 %K A240158 nonn %O A240158 1,1 %A A240158 _R. H. Hardin_, Apr 02 2014