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 A208100 #10 May 18 2020 18:59:09 %S A208100 1,52,10900,43366459,746823293346,37155328943771767, %T A208100 4226534204353128532380,947741983969338430602294081, %U A208100 378161752496622695975714927056844,249107761813131722624691729833262083766,255811781476365074058962776043470702114960079 %N A208100 Number of 5 X n nonnegative integer arrays with new values 0 upwards introduced in row major order and no element equal to any horizontal, diagonal or antidiagonal neighbor (colorings ignoring permutations of colors). %H A208100 Andrew Howroyd, <a href="/A208100/b208100.txt">Table of n, a(n) for n = 0..100</a> %e A208100 Some solutions for n=4: %e A208100 ..0..1..0..1....0..1..0..1....0..1..0..1....0..1..0..1....0..1..0..1 %e A208100 ..0..1..2..1....0..2..0..1....0..1..0..1....0..1..0..1....0..1..0..1 %e A208100 ..0..1..0..1....0..1..0..1....0..1..0..1....0..1..0..1....2..1..0..3 %e A208100 ..0..1..0..1....0..2..0..1....0..1..0..1....0..1..2..1....0..1..0..1 %e A208100 ..3..1..0..1....0..1..3..1....0..1..0..1....0..1..0..1....0..3..0..1 %Y A208100 Row 5 of A208096. %K A208100 nonn %O A208100 0,2 %A A208100 _R. H. Hardin_, Feb 23 2012 %E A208100 a(0)=1 prepended and terms a(6) and beyond from _Andrew Howroyd_, May 18 2020