%I A140177
%S A140177 1,4,25,171,1024,5452,27319,133343,650240,3183136,15730003,78792479,
%T A140177 401274724
%N A140177 Half the number of n X n symmetric binary matrices with adjacent rows 
               differing in at most two positions.
%Y A140177 Sequence in context: A006880 A081068 A163072 this_sequence A034494 A084210 
               A093683
%Y A140177 Adjacent sequences: A140174 A140175 A140176 this_sequence A140178 A140179 
               A140180
%K A140177 nonn
%O A140177 1,2
%A A140177 Ron Hardin (rhhardin(AT)att.net), Jun 15 2008