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 A207979 #9 Mar 15 2023 16:27:11 %S A207979 5,67,4192,587208,147512732,58668937932,34119101220224, %T A207979 27451586022436696,29334574202437277520,40343697156563884675488, %U A207979 69646199705725564208484736,147875840329637502384856552096,379682313150983568999164195148800 %N A207979 Number of n X 3 nonnegative integer arrays with new values 0 upwards introduced in row major order and no element equal to any diagonal or antidiagonal neighbor (colorings ignoring permutations of colors). %H A207979 Andrew Howroyd, <a href="/A207979/b207979.txt">Table of n, a(n) for n = 1..190</a> (terms 1..16 from R. H. Hardin) %e A207979 Some solutions for n=4 %e A207979 ..0..0..0....0..0..0....0..0..1....0..0..0....0..0..0....0..0..0....0..1..0 %e A207979 ..1..1..1....1..1..1....1..2..1....1..1..2....1..1..1....1..2..1....2..1..0 %e A207979 ..0..2..2....2..0..2....1..2..0....2..0..0....0..2..0....0..0..0....0..1..3 %e A207979 ..1..1..0....1..0..1....0..2..0....3..1..4....1..1..0....2..1..1....0..4..0 %Y A207979 Column 3 of A207981. %K A207979 nonn %O A207979 1,1 %A A207979 _R. H. Hardin_, Feb 22 2012