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%I #5 Dec 18 2015 18:17:43
%S 7,120,2424,139320,19924728,7436532066,7374601234200,
%T 19007056742693388,127460953360341764580,2242822081859232960548754
%N Number of n X n symmetric 0..6 arrays with no element equal to the sum or difference mod 7 of any two of its horizontal and vertical neighbors
%e Some solutions for 4X4
%e ..5..2..1..2....3..1..6..4....1..1..3..1....4..4..4..3....3..4..4..4
%e ..2..2..2..2....1..6..6..1....1..1..3..1....4..4..3..3....4..3..3..2
%e ..1..2..2..5....6..6..6..1....3..3..1..6....4..3..3..2....4..3..4..3
%e ..2..2..5..6....4..1..1..3....1..1..6..3....3..3..2..3....4..2..3..2
%K nonn
%O 1,1
%A _R. H. Hardin_ Aug 05 2011
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