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 A240372 #6 Jun 02 2025 09:51:53 %S A240372 4,21,75,450,1729,7233,36148,139855,645733,2919837,11900426,55182313, %T A240372 238587617,1020077489,4627613220,19831142375,86874931360,386104242606, %U A240372 1664229710205,7344843690603,32253553194721,140150173949016 %N A240372 Number of nX3 0..3 arrays with no element equal to one plus the sum of elements to its left or one plus the sum of elements above it or zero plus the sum of the elements diagonally to its northwest, modulo 4. %C A240372 Column 3 of A240376 %H A240372 R. H. Hardin, <a href="/A240372/b240372.txt">Table of n, a(n) for n = 1..210</a> %e A240372 Some solutions for n=4 %e A240372 ..3..2..3....3..2..3....3..2..3....3..2..3....2..2..2....3..3..2....3..3..2 %e A240372 ..3..2..1....3..2..1....2..0..1....3..2..1....2..0..0....2..2..2....3..2..0 %e A240372 ..2..0..2....2..2..3....3..1..2....2..0..2....3..1..0....3..1..3....2..0..0 %e A240372 ..3..3..1....2..0..2....2..1..2....3..3..0....2..2..0....2..1..1....3..3..0 %K A240372 nonn %O A240372 1,1 %A A240372 _R. H. Hardin_, Apr 04 2014