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 A207998 #9 Jul 01 2017 23:00:17 %S A207998 2,15,114,1657,36401,1094076,42436913,2042803419,118645071202, %T A207998 8138047375093,648222594284197,59148486677131940,6113429673418115581, %U A207998 708972517372901061559,91508202542991877872978,13053785934982985242672065 %N A207998 Number of nX2 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 A207998 Andrew Howroyd, <a href="/A207998/b207998.txt">Table of n, a(n) for n = 1..100</a> %e A207998 Some solutions for n=4 %e A207998 ..0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0 %e A207998 ..0..0....1..1....0..1....0..1....1..0....0..0....1..1....0..0....0..0....0..0 %e A207998 ..1..1....1..1....1..1....1..1....1..1....1..1....1..1....1..1....1..2....1..1 %e A207998 ..2..1....0..0....0..1....0..2....1..0....1..2....0..2....1..1....3..2....2..2 %Y A207998 Column 2 of A208001. %K A207998 nonn %O A207998 1,1 %A A207998 _R. H. Hardin_, Feb 22 2012 %E A207998 Terms a(16) and beyond from _Andrew Howroyd_, Jul 01 2017