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 A240403 #6 Jun 02 2025 09:54:52 %S A240403 4,24,235,1304,13648,98837,692520,6686074,47001423,368795251, %T A240403 3172886576,22843492846,188803534301,1516806583206,11402126592178, %U A240403 94073248811059,733120766691045,5706868084005386,46267999865467117,358824411389642466 %N A240403 Number of nX4 0..3 arrays with no element equal to one plus the sum of elements to its left or three plus the sum of elements above it or zero plus the sum of the elements diagonally to its northwest, modulo 4. %C A240403 Column 4 of A240406 %H A240403 R. H. Hardin, <a href="/A240403/b240403.txt">Table of n, a(n) for n = 1..210</a> %e A240403 Some solutions for n=4 %e A240403 ..2..1..1..2....2..1..2..1....2..1..1..2....2..1..1..2....2..1..2..1 %e A240403 ..2..1..2..3....3..1..2..1....2..1..2..0....3..3..2..2....3..3..2..3 %e A240403 ..2..0..0..2....3..2..1..2....2..0..0..2....3..2..3..2....2..2..2..2 %e A240403 ..3..3..0..0....2..1..2..1....2..0..1..1....2..0..0..2....3..3..0..0 %K A240403 nonn %O A240403 1,1 %A A240403 _R. H. Hardin_, Apr 04 2014