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 A239596 #6 Jun 02 2025 09:29:17 %S A239596 24,64,187,643,1737,7461,24946,78667,313003,946740,3353070,11758390, %T A239596 36733281,134840254,447239565,1494320065,5328884020,17359223415, %U A239596 60336682303,207461258909,687759739866,2406912915998,8088972710842 %N A239596 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 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 A239596 Column 4 of A239599 %H A239596 R. H. Hardin, <a href="/A239596/b239596.txt">Table of n, a(n) for n = 1..210</a> %e A239596 Some solutions for n=4 %e A239596 ..3..2..2..0....2..0..0..3....3..0..0..0....3..0..0..0....3..0..0..0 %e A239596 ..2..1..0..2....2..0..3..3....2..3..3..2....2..3..2..0....2..3..0..2 %e A239596 ..3..2..2..0....3..2..2..2....3..1..1..2....3..1..2..0....3..2..2..2 %e A239596 ..2..3..2..0....2..1..0..0....3..2..2..2....3..2..3..2....2..3..0..2 %K A239596 nonn %O A239596 1,1 %A A239596 _R. H. Hardin_, Mar 22 2014