%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