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 A222569 #6 Apr 21 2021 14:38:11 %S A222569 4,10,56,435,4790,50535,547563,5815939,63130202,676152734,7328771224, %T A222569 79083695286,857913193954,9302185273377,101073333908828, %U A222569 1099637763169027,11970412457540599,130557727722965457,1423911243991041430 %N A222569 Number of n X 4 0..2 arrays with no more than floor(nX4/2) elements unequal to at least one horizontal, diagonal or antidiagonal neighbor, with new values introduced in row major 0..2 order. %C A222569 Column 4 of A222573. %H A222569 R. H. Hardin, <a href="/A222569/b222569.txt">Table of n, a(n) for n = 1..128</a> %e A222569 Some solutions for n=3 %e A222569 ..0..0..0..0....0..0..0..0....0..0..0..0....0..1..2..2....0..0..0..1 %e A222569 ..0..0..0..0....0..0..0..0....0..0..0..0....2..2..2..2....0..0..0..0 %e A222569 ..1..0..2..0....0..0..0..1....0..0..1..0....2..2..2..2....0..0..0..1 %Y A222569 Cf. A222573. %K A222569 nonn %O A222569 1,1 %A A222569 _R. H. Hardin_ Feb 25 2013