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 A240189 #6 Jun 02 2025 09:41:33 %S A240189 1,14,129,771,7170,44594,333607,2715035,17332017,134735700,1005601984, %T A240189 6796746485,52922791645,379298005594,2679740305873,20445193269447, %U A240189 144861185356798,1052585343798258,7856125918090405,55861298280154250 %N A240189 Number of nX4 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 three plus the sum of the elements diagonally to its northwest, modulo 4. %C A240189 Column 4 of A240192 %H A240189 R. H. Hardin, <a href="/A240189/b240189.txt">Table of n, a(n) for n = 1..210</a> %e A240189 Some solutions for n=4 %e A240189 ..2..0..0..0....2..0..0..0....2..0..0..0....2..0..0..0....2..0..0..0 %e A240189 ..1..3..2..0....1..2..0..2....1..0..0..2....1..0..2..2....1..3..2..0 %e A240189 ..1..3..1..0....1..2..0..2....1..2..0..2....2..3..0..0....2..1..2..2 %e A240189 ..2..1..2..2....2..3..0..2....2..1..0..2....1..2..0..2....1..3..3..1 %K A240189 nonn %O A240189 1,2 %A A240189 _R. H. Hardin_, Apr 02 2014