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 A241441 #5 Jun 02 2025 10:09:32 %S A241441 24,9,1005,20690,218885,4136727,79901137,1058201862,16609740868 %N A241441 Number of 7Xn 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 zero 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 A241441 Row 7 of A241435 %e A241441 Some solutions for n=3 %e A241441 ..3..3..2....3..3..2....2..2..3....2..2..3....3..2..3....2..2..3....3..3..2 %e A241441 ..2..2..2....2..2..0....2..1..3....2..1..3....2..1..3....2..1..3....2..2..2 %e A241441 ..3..1..3....3..3..2....3..1..2....3..1..0....3..1..2....3..3..2....3..1..2 %e A241441 ..2..1..2....2..0..2....2..2..2....3..2..0....2..0..0....2..1..2....3..1..2 %e A241441 ..2..1..3....2..0..2....3..1..2....2..2..2....2..0..0....3..1..2....2..2..2 %e A241441 ..3..3..0....2..0..0....2..2..2....2..0..2....3..3..0....3..2..0....3..1..2 %e A241441 ..2..2..0....2..0..0....2..1..2....2..0..0....2..2..0....2..0..2....3..2..0 %K A241441 nonn %O A241441 1,1 %A A241441 _R. H. Hardin_, Apr 22 2014