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 A267724 #6 Aug 12 2016 06:55:35 %S A267724 0,1,0,1,1,0,1,1,2,0,1,3,2,6,0,1,5,30,6,24,0,1,12,58,630,24,120,0,1, %T A267724 26,588,1398,22680,120,720,0,1,60,2388,93672,55896,1247400,720,5040,0, %U A267724 1,143,17456,609264,33807456,3353880,97297200,5040,40320,0,1,353,102874 %N A267724 T(n,k)=Number of nXk arrays containing k copies of 0..n-1 with every element equal to at least one horizontal neighbor and the top left element equal to 0. %C A267724 Table starts %C A267724 .0......1.....1...........1.........1...........1.........1........1.........1 %C A267724 .0......1.....1...........3.........5..........12........26.......60.......143 %C A267724 .0......2.....2..........30........58.........588......2388....17456....102874 %C A267724 .0......6.....6.........630......1398.......93672....609264.20702760.279681294 %C A267724 .0.....24....24.......22680.....55896....33807456.331295040 %C A267724 .0....120...120.....1247400...3353880.22933860480 %C A267724 .0....720...720....97297200.281725200 %C A267724 .0...5040..5040.10216206000 %C A267724 .0..40320.40320 %C A267724 .0.362880 %H A267724 R. H. Hardin, <a href="/A267724/b267724.txt">Table of n, a(n) for n = 1..70</a> %e A267724 Some solutions for n=4 k=4 %e A267724 ..0..0..2..2....0..0..0..0....0..0..1..1....0..0..2..2....0..0..3..3 %e A267724 ..2..2..0..0....3..3..3..3....3..3..2..2....1..1..0..0....1..1..2..2 %e A267724 ..1..1..3..3....2..2..1..1....0..0..2..2....3..3..2..2....1..1..2..2 %e A267724 ..3..3..1..1....2..2..1..1....3..3..1..1....3..3..1..1....0..0..3..3 %Y A267724 Column 2 and column 3 are A000142(n-1). %Y A267724 Column 4 is A007019(n-1). %K A267724 nonn,tabl %O A267724 1,9 %A A267724 _R. H. Hardin_, Jan 20 2016