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 A240891 #6 Jul 23 2025 11:08:11 %S A240891 16,376,7609,154858,3146755,64074526,1302610899,26501432610, %T A240891 539075345618,10966382557858,223082242117552,4538081394098364, %U A240891 92316133808933027,1877950089801487198,38202362639765816422,777135231123406032012 %N A240891 Number of nX6 0..2 arrays with no element equal to a different number of vertical neighbors than horizontal neighbors, with new values 0..2 introduced in row major order. %C A240891 Column 6 of A240893 %H A240891 R. H. Hardin, <a href="/A240891/b240891.txt">Table of n, a(n) for n = 1..210</a> %e A240891 Some solutions for n=4 %e A240891 ..0..1..2..0..2..1....0..1..0..1..0..1....0..1..0..2..1..0....0..0..1..0..1..0 %e A240891 ..1..0..1..2..1..0....1..0..2..0..1..0....1..0..2..0..2..1....0..0..2..1..0..1 %e A240891 ..0..2..0..1..2..1....0..2..1..2..0..1....0..2..0..1..1..0....2..1..0..2..1..0 %e A240891 ..2..0..1..2..1..2....2..1..2..0..1..2....1..0..2..1..1..2....1..0..2..1..0..2 %K A240891 nonn %O A240891 1,1 %A A240891 _R. H. Hardin_, Apr 14 2014