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 A208093 #11 Jun 02 2025 07:43:05 %S A208093 2,30,1573,192328,43366459,15769674462,8494585220016,6391850672195207, %T A208093 6435536606760976374,8388789053759733374255, %U A208093 13792349692923790472807338,28002764873470436036725295426,68986219453948522377865096287773 %N A208093 Number of nX3 nonnegative integer arrays with new values 0 upwards introduced in row major order and no element equal to any horizontal, diagonal or antidiagonal neighbor (colorings ignoring permutations of colors). %C A208093 Column 3 of A208096 %H A208093 R. H. Hardin, <a href="/A208093/b208093.txt">Table of n, a(n) for n = 1..16</a> %e A208093 Some solutions for n=4 %e A208093 ..0..1..2....0..1..0....0..1..0....0..1..2....0..1..0....0..1..0....0..1..0 %e A208093 ..0..1..2....2..1..0....0..1..0....0..3..0....0..1..0....2..3..0....0..1..0 %e A208093 ..0..1..0....3..1..2....0..1..0....0..1..0....2..1..2....0..3..0....0..1..2 %e A208093 ..0..1..0....2..1..0....0..2..3....0..3..0....0..1..0....0..1..0....0..1..0 %K A208093 nonn %O A208093 1,1 %A A208093 _R. H. Hardin_ Feb 23 2012