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%I #4 Dec 18 2015 18:18:12
%S 3,126,28328,29365738,124477495732
%N Number of n X n 0..6 matrices whose square is also a 0..6 matrix
%C Column 6 of A213990
%e Some.solutions.for.n=3
%e ..2..0..1....0..1..0....0..6..4....0..3..6....0..4..0....0..5..0....0..0..4
%e ..0..1..6....0..0..1....0..1..0....0..1..0....0..0..0....0..1..0....0..1..3
%e ..0..0..0....3..3..0....0..0..0....0..0..0....1..5..0....0..3..0....0..1..1
%K nonn
%O 1,1
%A _R. H. Hardin_ Jun 30 2012