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Number of n X n 0..2 symmetric matrices with every element equal to zero or two horizontal and vertical neighbors, and new values 0..2 introduced in lower triangle row major order
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%I #5 Dec 18 2015 18:18:05

%S 1,3,17,199,3494,98664,4322895,299203520,32406437104,5516394350943,

%T 1472647280151852,617087491407309762,405686597596735406852

%N Number of n X n 0..2 symmetric matrices with every element equal to zero or two horizontal and vertical neighbors, and new values 0..2 introduced in lower triangle row major order

%e Some solutions for n=3

%e ..0..1..0....0..1..0....0..1..2....0..0..1....0..1..2....0..1..2....0..1..2

%e ..1..0..1....1..2..1....1..2..1....0..0..2....1..2..0....1..0..0....1..2..1

%e ..0..1..2....0..1..2....2..1..0....1..2..1....2..0..1....2..0..0....2..1..2

%K nonn

%O 1,2

%A _R. H. Hardin_ Mar 29 2012