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%I #5 Dec 18 2015 18:18:06
%S 1,3,23,401,13984,970083,132838634,35924634547,19142194392682,
%T 20077037322761989,41429745313369193161,168164789977096418548306
%N Number of n X n 0..2 symmetric matrices with every element equal to zero, two or three horizontal and vertical neighbors, and new values 0..2 introduced in lower triangle row major order
%e Some solutions for n=4
%e ..0..1..0..0....0..1..0..1....0..1..2..2....0..1..0..0....0..1..0..1
%e ..1..0..0..0....1..2..2..0....1..2..2..2....1..2..0..0....1..2..2..2
%e ..0..0..1..0....0..2..2..1....2..2..0..1....0..0..2..0....0..2..2..2
%e ..0..0..0..0....1..0..1..0....2..2..1..2....0..0..0..0....1..2..2..0
%K nonn
%O 1,2
%A _R. H. Hardin_ Mar 29 2012
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