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 A207999 #7 Jul 01 2017 23:00:23 %S A207999 5,114,4141,426422,86545486,29169661126,14823734802701, %T A207999 10648697150313375,10321527909363771779,13032394645031912097587, %U A207999 20852865726433378283251197,41354508341339617041441302471,99804566252370862012176094395266,288659258928461717629676421776606809 %N A207999 Number of nX3 nonnegative integer arrays with new values 0 upwards introduced in row major order and no element equal to any knight-move neighbor (colorings ignoring permutations of colors). %H A207999 Andrew Howroyd, <a href="/A207999/b207999.txt">Table of n, a(n) for n = 1..50</a> %e A207999 Some solutions for n=4 %e A207999 ..0..0..0....0..1..0....0..0..0....0..0..0....0..0..0....0..1..2....0..0..0 %e A207999 ..1..0..1....1..0..1....1..2..1....1..0..1....1..0..1....0..0..1....1..0..1 %e A207999 ..2..1..2....0..1..2....2..1..2....2..1..2....2..2..2....0..1..2....2..1..2 %e A207999 ..1..2..1....1..2..1....3..0..0....1..0..3....1..0..1....1..2..1....1..0..1 %Y A207999 Column 3 of A208001. %K A207999 nonn %O A207999 1,1 %A A207999 _R. H. Hardin_, Feb 22 2012 %E A207999 Terms a(8) and beyond from _Andrew Howroyd_, Jul 01 2017