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 A239597 #6 May 03 2021 15:11:28 %S A239597 56,244,1310,8773,38824,282333,1583770,8002162,56967196,275601241, %T A239597 1652784297,9647550002,46816042965,300001108431,1594217578916, %U A239597 8755494803789,53058504883026,272797119276412,1625241123981520 %N A239597 Number of n X 5 0..3 arrays with no element equal to zero plus the sum of elements to its left or one plus the sum of 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 A239597 Column 5 of A239599. %H A239597 R. H. Hardin, <a href="/A239597/b239597.txt">Table of n, a(n) for n = 1..40</a> %e A239597 Some solutions for n=4 %e A239597 ..2..3..2..0..2....3..0..0..2..0....3..2..2..0..2....3..2..2..2..2 %e A239597 ..2..1..2..2..0....2..3..2..2..2....2..1..2..2..2....2..1..0..1..2 %e A239597 ..3..2..2..0..2....3..2..0..0..0....3..2..2..2..2....3..2..2..2..2 %e A239597 ..2..1..0..0..0....2..1..2..2..0....2..1..0..0..0....2..1..0..1..2 %Y A239597 Cf. A239599. %K A239597 nonn %O A239597 1,1 %A A239597 _R. H. Hardin_, Mar 22 2014