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 A233258 #8 Oct 11 2018 05:40:09 %S A233258 11,136,4672,166400,6049792,220626944,8050180096,293762760704, %T A233258 10720053821440,391200251052032,14275841005453312,520959990903603200, %U A233258 19011091850007150592,693760794065113186304,25317011997007519154176 %N A233258 Number of 3 X n 0..5 arrays with no element x(i,j) adjacent to itself or value 5-x(i,j) horizontally or antidiagonally, top left element zero, and 1 appearing before 2 3 and 4, and 2 appearing before 3 in row major order (unlabelled 6-colorings with no clashing color pairs). %H A233258 R. H. Hardin, <a href="/A233258/b233258.txt">Table of n, a(n) for n = 1..210</a> %F A233258 Empirical: a(n) = 48*a(n-1) - 448*a(n-2) + 1024*a(n-3) for n>5. %F A233258 Empirical g.f.: x*(11 - 392*x + 3072*x^2 - 8192*x^3 + 16384*x^4) / ((1 - 8*x)*(1 - 40*x + 128*x^2)). - _Colin Barker_, Oct 11 2018 %e A233258 Some solutions for n=3: %e A233258 ..0..1..5....0..1..5....0..1..2....0..1..2....0..1..2....0..1..2....0..1..2 %e A233258 ..5..2..5....5..2..0....3..1..3....0..4..5....2..5..3....3..1..5....5..1..2 %e A233258 ..1..3..5....4..2..0....5..1..2....0..2..4....1..0..2....5..4..3....5..4..0 %Y A233258 Row 3 of A233256. %K A233258 nonn %O A233258 1,1 %A A233258 _R. H. Hardin_, Dec 06 2013