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 A231396 #6 Jul 23 2025 06:27:32 %S A231396 3,7,4,14,8,7,33,38,15,12,78,90,100,20,23,189,363,311,272,31,44,482, %T A231396 1163,1706,1096,740,52,87,1225,3985,7844,8340,4085,2061,95,172,3238, %U A231396 14650,35696,55788,41237,15732,5834,180,343,8565,50088,184692,345022,401240 %N A231396 T(n,k)=Number of (n+1)X(k+1) 0..2 arrays with no element unequal to a strict majority of its horizontal, diagonal and antidiagonal neighbors, with values 0..2 introduced in row major order. %C A231396 Table starts %C A231396 ...3...7.....14......33........78........189........482.......1225.......3238 %C A231396 ...4...8.....38......90.......363.......1163.......3985......14650......50088 %C A231396 ...7..15....100.....311......1706.......7844......35696.....184692.....873979 %C A231396 ..12..20....272....1096......8340......55788.....345022....2502891...16525492 %C A231396 ..23..31....740....4085.....41237.....401240....3407422...34218952..319475231 %C A231396 ..44..52...2061...15732....217846....3002376...35510853..491895476.6459555901 %C A231396 ..87..95...5834...62039...1158551...22654165..374180527.7170248270 %C A231396 .172.180..16521..245850...6261166..172363558.3979476204 %C A231396 .343.351..46969..980361..34110556.1318257485 %C A231396 .684.692.133864.3915982.186830745 %H A231396 R. H. Hardin, <a href="/A231396/b231396.txt">Table of n, a(n) for n = 1..111</a> %F A231396 Empirical for column k: %F A231396 k=1: a(n) = 2*a(n-1) +a(n-2) -2*a(n-3) %F A231396 k=2: a(n) = 2*a(n-1) +a(n-2) -2*a(n-3) for n>5 %F A231396 k=3: [order 18] %F A231396 k=4: [order 28] for n>31 %F A231396 Empirical for row n: %F A231396 n=1: a(n) = 4*a(n-1) +a(n-2) -16*a(n-3) +4*a(n-4) +24*a(n-5) -16*a(n-6) %F A231396 n=2: [order 21] %F A231396 n=3: [order 83] %e A231396 Some solutions for n=4 k=4 %e A231396 ..0..0..0..0..0....0..0..1..1..1....0..0..1..1..1....0..1..1..1..1 %e A231396 ..1..1..0..0..0....1..1..0..0..0....0..1..0..1..1....1..0..0..0..0 %e A231396 ..1..1..1..0..0....1..1..1..0..0....1..0..1..0..0....1..1..0..0..0 %e A231396 ..1..1..0..0..0....1..1..0..0..0....1..1..0..0..0....1..1..1..2..2 %e A231396 ..1..1..1..0..0....0..0..0..0..0....1..1..1..1..1....1..1..2..2..2 %Y A231396 Column 1 is A023105(n+2) %K A231396 nonn,tabl %O A231396 1,1 %A A231396 _R. H. Hardin_, Nov 08 2013