%I A140178
%S A140178 1,4,32,427,7396,130612,2097152,30417025,409957616,5282779354
%N A140178 Half the number of n X n symmetric binary matrices with adjacent rows 
               differing in at most three positions.
%Y A140178 Sequence in context: A113131 A127670 A005172 this_sequence A088991 A009668 
               A005121
%Y A140178 Adjacent sequences: A140175 A140176 A140177 this_sequence A140179 A140180 
               A140181
%K A140178 nonn
%O A140178 1,2
%A A140178 Ron Hardin (rhhardin(AT)att.net), Jun 15 2008