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 A240267 #6 Jun 02 2025 09:44:51 %S A240267 10,35,118,582,2000,8353,37422,135463,580528,2403439,9094559,38858731, %T A240267 155489063,610603047,2566277060,10164936522,40839681679,168734662196, %U A240267 669445744507,2718398151862,11090164669401,44257273047277 %N A240267 Number of nX3 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, modulo 4. %C A240267 Column 3 of A240271 %H A240267 R. H. Hardin, <a href="/A240267/b240267.txt">Table of n, a(n) for n = 1..210</a> %e A240267 Some solutions for n=4 %e A240267 ..2..3..2....3..2..0....3..2..3....3..2..2....3..2..2....3..2..3....3..2..2 %e A240267 ..2..1..1....2..1..0....3..2..2....2..1..2....3..1..2....3..1..2....3..1..2 %e A240267 ..2..0..3....3..2..2....2..3..3....3..2..2....2..3..2....2..3..3....2..3..3 %e A240267 ..2..0..1....2..3..0....2..1..2....2..3..0....3..0..2....3..0..2....3..2..2 %K A240267 nonn %O A240267 1,1 %A A240267 _R. H. Hardin_, Apr 03 2014