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 A239998 #6 Jun 02 2025 09:37:11 %S A239998 6,65,1262,27415,635873,15981219,429788876,12392346376,378942837634, %T A239998 12142601105289,402528634881777,13658205122550505,470581987400700236, %U A239998 16373110177063830815,573193391287239428978,20143454978776804982736 %N A239998 Number of nX5 0..3 arrays with no element equal to one plus the sum of elements to its left or two plus the sum of elements above it or one plus the sum of the elements diagonally to its northwest, modulo 4. %C A239998 Column 5 of A240000 %H A239998 R. H. Hardin, <a href="/A239998/b239998.txt">Table of n, a(n) for n = 1..210</a> %e A239998 Some solutions for n=4 %e A239998 ..0..3..3..0..0....0..0..0..3..3....3..3..0..0..0....0..3..3..0..0 %e A239998 ..0..2..2..3..3....3..3..0..0..2....0..2..1..3..0....0..2..2..3..3 %e A239998 ..3..2..0..3..0....0..3..1..2..2....2..2..0..3..3....0..0..0..0..0 %e A239998 ..3..2..1..1..3....3..2..0..0..0....2..0..1..1..2....0..0..2..0..0 %K A239998 nonn %O A239998 1,1 %A A239998 _R. H. Hardin_, Mar 30 2014