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 A208297 #8 Jun 02 2025 07:43:13 %S A208297 2,42,2906,433252,113503692,46538017584,27700815674032, %T A208297 22702140562948192,24626774613248937584,34296243004533645925408, %U A208297 59839415643338575851475744,128222446504879248765189962560,331858429902640216546970620625280 %N A208297 Number of nX3 nonnegative integer arrays with new values 0 upwards introduced in row major order and no element equal to any horizontal or antidiagonal neighbor (colorings ignoring permutations of colors). %C A208297 Column 3 of A208301 %H A208297 R. H. Hardin, <a href="/A208297/b208297.txt">Table of n, a(n) for n = 1..49</a> %e A208297 Some solutions for n=4 %e A208297 ..0..1..0....0..1..0....0..1..2....0..1..0....0..1..0....0..1..2....0..1..2 %e A208297 ..0..1..0....0..1..0....0..1..2....0..1..0....2..3..0....0..3..1....0..3..0 %e A208297 ..0..1..0....2..1..2....0..1..0....0..1..0....0..2..0....0..2..0....0..1..0 %e A208297 ..0..2..1....0..1..0....0..1..0....0..1..0....0..1..0....3..1..0....0..3..0 %K A208297 nonn %O A208297 1,1 %A A208297 _R. H. Hardin_ Feb 25 2012