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A211913 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, diagonal or antidiagonal neighbor, and containing the value n(n+1)/2-4.

%I A211913 #6 Jun 02 2025 07:51:47
%S A211913 0,0,10,802,27963,394117,3243531,18826250,85484512,323341343,
%T A211913 1061434357,3110902786,8308425940
%N A211913 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, diagonal or antidiagonal neighbor, and containing the value n(n+1)/2-4.
%C A211913 Column 3 of A211916
%e A211913 Some solutions for n=4
%e A211913 ..0........0........0........0........0........0........0........0
%e A211913 ..1.2......1.2......1.2......1.2......1.2......1.2......1.2......1.2
%e A211913 ..0.3.4....3.4.5....3.0.4....3.4.0....3.4.5....0.3.4....0.3.4....3.4.5
%e A211913 ..5.6.0.5..0.1.6.7..4.5.6.0..5.6.7.6..2.1.6.3..5.2.6.7..4.5.6.1..1.6.2.1
%K A211913 nonn
%O A211913 1,3
%A A211913 _R. H. Hardin_ Apr 25 2012