%I #8 Nov 21 2014 03:55:35
%S 6,109,2785,160273,31474553,21334488089,46140355278097,
%T 306619332905168069,6168636777847547479765
%N Number of n X n symmetric 0..5 arrays with no element equal to the difference mod 6 of any two of its horizontal and vertical neighbors.
%e Some solutions for 4 X 4:
%e ..5..0..2..1....2..3..4..2....3..3..2..2....5..0..3..1....1..3..0..1
%e ..0..4..1..2....3..4..3..3....3..1..3..3....0..2..0..0....3..1..0..3
%e ..2..1..2..2....4..3..4..2....2..3..3..4....3..0..1..3....0..0..4..0
%e ..1..2..2..3....2..3..2..3....2..3..4..2....1..0..3..5....1..3..0..1
%K nonn
%O 1,1
%A _R. H. Hardin_, Aug 05 2011
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