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 A222374 #6 Jul 23 2025 02:32:44 %S A222374 1,5,9,118,498,8111,37107,676485,3140167,58995438,275054103, %T A222374 5223616489,24395423052,466212749842,2180168118272,41855166855421, %U A222374 195981171753608,3775984650279490,17703134058396750,342076192235557748 %N A222374 Number of nX3 0..3 arrays with no more than floor(nX3/2) elements unequal to at least one horizontal or vertical neighbor, with new values introduced in row major 0..3 order. %C A222374 Column 3 of A222378 %H A222374 R. H. Hardin, <a href="/A222374/b222374.txt">Table of n, a(n) for n = 1..130</a> %e A222374 Some solutions for n=4 %e A222374 ..0..1..0....0..0..0....0..0..1....0..0..0....0..0..0....0..0..1....0..0..0 %e A222374 ..0..0..0....1..0..0....2..2..2....0..0..0....0..0..0....1..1..1....0..0..0 %e A222374 ..0..0..0....1..1..1....2..2..2....0..0..1....1..0..0....1..1..1....0..1..0 %e A222374 ..0..0..0....1..1..1....2..2..2....0..0..1....1..0..0....1..1..1....1..0..0 %K A222374 nonn %O A222374 1,2 %A A222374 _R. H. Hardin_ Feb 17 2013