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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)/2-7
0

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

%S 0,0,0,6093,8826873,3020833719,276214923832,11092305676290

%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)/2-7

%C Column 6 of A211930

%e Some solutions for n=4

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

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

%e ..3.1.3....0.3.2....2.3.2....0.3.4....3.1.4....0.3.2....3.1.4....3.4.0

%e ..2.4.2.0..4.1.4.1..4.1.5.2..5.2.0.3..5.2.5.1..1.4.5.0..5.2.3.2..5.1.4.3

%K nonn

%O 1,4

%A _R. H. Hardin_ Apr 25 2012