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 A208000 #7 Jul 01 2017 23:00:31 %S A208000 15,1657,426422,450288795,1182700979380,6184248124218800, %T A208000 56513375910372605548,826725568737937330039810, %U A208000 18171823971396715681105965282,572057633247843506849301892746850,24840621984533068280588275487942834483,1443495070617319156132945205013820325621405 %N A208000 Number of nX4 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 A208000 Andrew Howroyd, <a href="/A208000/b208000.txt">Table of n, a(n) for n = 1..50</a> %e A208000 Some solutions for n=4 %e A208000 ..0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0 %e A208000 ..1..1..1..1....1..1..1..1....1..1..1..1....1..1..1..2....1..1..1..1 %e A208000 ..2..2..2..3....2..2..2..2....2..2..2..2....2..1..2..2....2..2..2..2 %e A208000 ..0..0..0..0....0..0..0..0....3..3..0..0....0..0..3..4....0..0..3..0 %Y A208000 Column 4 of A208001. %K A208000 nonn %O A208000 1,1 %A A208000 _R. H. Hardin_, Feb 22 2012 %E A208000 Terms a(6) and beyond from _Andrew Howroyd_, Jul 01 2017