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%I #5 Dec 18 2015 18:18:06
%S 0,1,2,49,3312,818235,488196032,845278581938,3889846475035188,
%T 49699973559580684560
%N Number of n X n 0..3 symmetric matrices with every element equal to one or two horizontal and vertical neighbors, and new values 0..3 introduced in lower triangle row major order
%e Some solutions for n=4
%e ..0..0..1..1....0..0..1..0....0..0..1..1....0..0..2..2....0..0..1..0
%e ..0..0..2..0....0..1..1..0....0..0..1..1....0..1..1..1....0..0..1..0
%e ..1..2..2..0....1..1..2..2....1..1..2..2....2..1..0..0....1..1..1..0
%e ..1..0..0..0....0..0..2..2....1..1..2..2....2..1..0..0....0..0..0..0
%K nonn
%O 1,3
%A _R. H. Hardin_ Mar 29 2012