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Number of lower triangular n X n arrays colored with integers 0 upwards introduced in row major order, with no element equal to any horizontal, vertical or antidiagonal neighbor, and containing the value n(n+1)/2-4
0

%I #4 Dec 18 2015 18:18:09

%S 0,0,27,1685,43607,529891,4014522,22135982,97128215,358619827,

%T 1156561481,3344471967,8839393862

%N Number of lower triangular n X n arrays colored with integers 0 upwards introduced in row major order, with no element equal to any horizontal, vertical or antidiagonal neighbor, and containing the value n(n+1)/2-4

%C Column 3 of A211930

%e Some solutions for n=4

%e ..0........0........0........0........0........0........0........0

%e ..1.2......1.2......1.0......1.0......1.2......1.2......1.2......1.2

%e ..3.4.0....3.4.5....2.1.3....2.3.0....3.4.2....3.0.4....3.4.5....3.4.1

%e ..5.1.6.2..5.1.6.4..4.5.6.2..4.2.5.6..5.6.1.2..5.1.6.2..6.3.1.6..5.3.6.1

%K nonn

%O 1,3

%A _R. H. Hardin_ Apr 25 2012