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 A269052 #4 Feb 18 2016 11:38:51 %S A269052 3,9,9,24,42,27,60,102,174,81,144,360,594,666,243,336,1068,3078,3258, %T A269052 2430,729,768,3288,13140,24192,17346,8586,2187,1728,9864,58752,149358, %U A269052 183072,90450,29646,6561,3840,29472,253416,971844,1643376,1350672,464250 %N A269052 T(n,k)=Number of nXk 0..2 arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling two not more than once. %C A269052 Table starts %C A269052 .....3.......9.......24.........60..........144............336.............768 %C A269052 .....9......42......102........360.........1068...........3288............9864 %C A269052 ....27.....174......594.......3078........13140..........58752..........253416 %C A269052 ....81.....666.....3258......24192.......149358.........971844.........6053094 %C A269052 ...243....2430....17346.....183072......1643376.......15547380.......140497512 %C A269052 ...729....8586....90450....1350672.....17696520......242861616......3193266318 %C A269052 ..2187...29646...464250....9779808....187575858.....3726221592.....71430596250 %C A269052 ..6561..100602..2353338...69793968...1964080920....56376679620...1577976495486 %C A269052 .19683..336798.11809746..492374976..20365312416...843461153880..34509932303172 %C A269052 .59049.1115370.58773858.3441051984.209472681102.12504078167988.748499855355192 %H A269052 R. H. Hardin, <a href="/A269052/b269052.txt">Table of n, a(n) for n = 1..337</a> %F A269052 Empirical for column k: %F A269052 k=1: a(n) = 3*a(n-1) %F A269052 k=2: a(n) = 6*a(n-1) -9*a(n-2) for n>3 %F A269052 k=3: a(n) = 10*a(n-1) -29*a(n-2) +20*a(n-3) -4*a(n-4) for n>5 %F A269052 k=4: a(n) = 14*a(n-1) -57*a(n-2) +56*a(n-3) -16*a(n-4) for n>5 %F A269052 k=5: [order 12] for n>13 %F A269052 k=6: [order 18] for n>19 %F A269052 k=7: [order 38] for n>39 %F A269052 Empirical for row n: %F A269052 n=1: a(n) = 4*a(n-1) -4*a(n-2) %F A269052 n=2: a(n) = 4*a(n-1) -8*a(n-3) -4*a(n-4) %F A269052 n=3: a(n) = 6*a(n-1) -a(n-2) -28*a(n-3) -4*a(n-4) +16*a(n-5) -4*a(n-6) for n>8 %F A269052 n=4: [order 12] for n>14 %F A269052 n=5: [order 20] for n>22 %F A269052 n=6: [order 46] for n>48 %F A269052 n=7: [order 92] for n>94 %e A269052 Some solutions for n=4 k=4 %e A269052 ..1..2..2..1. .1..2..1..0. .0..1..2..2. .0..1..0..1. .2..1..0..1 %e A269052 ..2..2..2..1. .1..2..1..0. .2..1..2..1. .0..1..2..1. .2..1..2..1 %e A269052 ..1..2..2..2. .1..0..1..2. .1..2..2..1. .2..1..0..1. .2..1..2..1 %e A269052 ..1..2..1..2. .0..2..1..2. .1..2..2..2. .0..1..2..0. .2..1..2..1 %Y A269052 Column 1 is A000244. %Y A269052 Column 2 is A268622. %Y A269052 Row 1 is A084858. %K A269052 nonn,tabl %O A269052 1,1 %A A269052 _R. H. Hardin_, Feb 18 2016