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 A280858 #4 Jan 09 2017 09:37:30 %S A280858 224,6596,1698,1005,968,1202,1738,2877,5244,9569,15872,24653,36954, %T A280858 55077,83190,128817,204084,326793,522262,828099,1300592,2029441, %U A280858 3159306,4927841,7712840,12114811,19061740,29999825,47157384,74031085,116080358 %N A280858 Number of nX7 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 A280858 Column 7 of A280859. %H A280858 R. H. Hardin, <a href="/A280858/b280858.txt">Table of n, a(n) for n = 1..210</a> %F A280858 Empirical: a(n) = a(n-1) +a(n-2) -a(n-3) +a(n-4) -a(n-5) +2*a(n-6) -a(n-7) +6*a(n-8) -4*a(n-9) -4*a(n-12) -a(n-13) -2*a(n-14) -3*a(n-15) -3*a(n-16) +3*a(n-17) -3*a(n-18) +a(n-19) -a(n-20) +2*a(n-23) for n>29 %e A280858 Some solutions for n=4 %e A280858 ..0..0..1..1..2..1..2. .0..1..0..0..1..0..0. .0..1..1..2..1..2..2 %e A280858 ..1..2..2..0..0..1..0. .2..2..1..2..1..2..1. .2..2..0..2..0..0..1 %e A280858 ..1..0..1..1..2..2..0. .1..0..0..2..0..2..0. .0..1..0..1..1..2..1 %e A280858 ..2..0..2..0..0..1..1. .1..2..1..1..0..1..0. .0..1..2..2..0..2..0 %Y A280858 Cf. A280859. %K A280858 nonn %O A280858 1,1 %A A280858 _R. H. Hardin_, Jan 09 2017