%I #5 Mar 31 2012 12:37:34
%S 4,46,1139,55516,5327304,1010944060,380704421087,285205710360936,
%T 425825333933157003,1268871858354238286927,7554384371145384136117854,
%U 89942576436863983961350601461,2143078341798100623746679385130235
%N Number of (n+1)X(n+1) 0..2 symmetric matrices with every 2X2 subblock having one or two distinct values, and new values 0..2 introduced in lower triangle row major order
%H R. H. Hardin, <a href="/A210855/b210855.txt">Table of n, a(n) for n = 1..16</a>
%e Some solutions for n=3
%e ..0..1..1..0....0..1..2..2....0..1..1..1....0..0..0..0....0..1..0..0
%e ..1..0..1..1....1..1..1..1....1..1..2..1....0..0..0..0....1..1..1..1
%e ..1..1..1..0....2..1..2..2....1..2..2..2....0..0..0..0....0..1..1..0
%e ..0..1..0..0....2..1..2..0....1..1..2..2....0..0..0..1....0..1..0..1
%K nonn
%O 1,1
%A _R. H. Hardin_ Mar 28 2012