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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 or vertical neighbor, and containing the value n(n+1)/2-6
0

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

%S 0,0,42,11296,3997836,350026718,12075054829,228741733963

%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 or vertical neighbor, and containing the value n(n+1)/2-6

%C Column 5 of A211910

%e Some solutions for n=4

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

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

%e ..2.3.2....0.3.0....0.3.4....3.4.3....2.1.3....2.3.2....2.3.2....3.0.4

%e ..4.1.4.0..4.5.2.6..3.0.2.0..5.0.5.3..4.0.4.3..4.2.0.1..3.4.3.1..4.5.2.0

%K nonn

%O 1,3

%A _R. H. Hardin_ Apr 25 2012