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 A269289 #4 Feb 21 2016 09:27:23 %S A269289 4,16,16,60,216,64,216,2124,2592,256,756,19188,62748,29160,1024,2592, %T A269289 164556,1363572,1698732,314928,4096,8748,1363572,27788292,87559668, %U A269289 43674876,3306744,16384,29160,11026764,544118148,4204943820,5306911092 %N A269289 T(n,k)=Number of nXk 0..3 arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling three no more than once. %C A269289 Table starts %C A269289 ......4.........16.............60...............216...................756 %C A269289 .....16........216...........2124.............19188................164556 %C A269289 .....64.......2592..........62748...........1363572..............27788292 %C A269289 ....256......29160........1698732..........87559668............4204943820 %C A269289 ...1024.....314928.......43674876........5306911092..........598478857956 %C A269289 ...4096....3306744.....1085203980......309846524148........81907569617580 %C A269289 ..16384...34012224....26317946844....17623065834612.....10908770041709316 %C A269289 ..65536..344373768...626778812268...983118947312628...1424067311317705740 %C A269289 .262144.3443737680.14718495557052.54032675767734132.183070424003703987492 %H A269289 R. H. Hardin, <a href="/A269289/b269289.txt">Table of n, a(n) for n = 1..241</a> %F A269289 Empirical for column k: %F A269289 k=1: a(n) = 4*a(n-1) %F A269289 k=2: a(n) = 18*a(n-1) -81*a(n-2) %F A269289 k=3: a(n) = 42*a(n-1) -441*a(n-2) %F A269289 k=4: a(n) = 98*a(n-1) -2401*a(n-2) for n>3 %F A269289 k=5: a(n) = 234*a(n-1) -14277*a(n-2) +68796*a(n-3) -86436*a(n-4) %F A269289 k=6: [order 6] for n>7 %F A269289 k=7: [order 10] for n>11 %F A269289 Empirical for row n: %F A269289 n=1: a(n) = 6*a(n-1) -9*a(n-2) %F A269289 n=2: a(n) = 14*a(n-1) -49*a(n-2) for n>4 %F A269289 n=3: a(n) = 36*a(n-1) -378*a(n-2) +972*a(n-3) -729*a(n-4) for n>7 %F A269289 n=4: [order 8] for n>12 %F A269289 n=5: [order 18] for n>23 %F A269289 n=6: [order 40] for n>46 %e A269289 Some solutions for n=3 k=4 %e A269289 ..0..2..3..3. .0..2..3..1. .0..0..0..1. .0..2..2..2. .2..0..0..2 %e A269289 ..2..1..3..1. .2..1..0..2. .2..2..3..1. .0..2..0..0. .0..0..3..3 %e A269289 ..3..1..0..1. .1..0..2..0. .1..3..3..3. .2..0..0..2. .0..1..1..0 %Y A269289 Column 1 is A000302. %Y A269289 Column 2 is A159739(n+1). %Y A269289 Row 1 is A120926(n+1). %K A269289 nonn,tabl %O A269289 1,1 %A A269289 _R. H. Hardin_, Feb 21 2016