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 A280856 #4 Jan 09 2017 09:35:45 %S A280856 30,442,256,216,282,491,968,1857,3220,5281,8574,14339,24694,42833, %T A280856 73650,125361,212438,360727,614668,1049609,1791800,3055487,5205640, %U A280856 8868669,15113516,25765385,43926544,74885231,127643494,217567203,370837946 %N A280856 Number of nX5 0..2 arrays with no element equal to more than one of its king-move neighbors and with new values introduced in order 0 sequentially upwards. %C A280856 Column 5 of A280859. %H A280856 R. H. Hardin, <a href="/A280856/b280856.txt">Table of n, a(n) for n = 1..210</a> %F A280856 Empirical: a(n) = a(n-1) +a(n-2) -a(n-3) +2*a(n-4) -a(n-5) +4*a(n-6) -a(n-7) -a(n-8) -2*a(n-9) -3*a(n-12) for n>18 %e A280856 Some solutions for n=4 %e A280856 ..0..0..1..1..0. .0..1..1..2..1. .0..1..0..1..1. .0..1..0..0..1 %e A280856 ..1..2..2..0..2. .2..2..0..0..1. .0..2..0..2..0. .2..1..2..1..2 %e A280856 ..1..0..1..1..2. .0..1..1..2..2. .1..2..1..1..0. .0..0..2..0..2 %e A280856 ..0..2..2..0..0. .2..2..0..0..1. .1..0..0..2..2. .2..1..1..0..1 %Y A280856 Cf. A280859. %K A280856 nonn %O A280856 1,1 %A A280856 _R. H. Hardin_, Jan 09 2017