%I A162057
%S A162057 2,6,13,34,86,233,652,1888,5683,17526,55868,182024,609103,2081152,
%T A162057 7268823,25891230,93983793,347398900,1306005890,4991876362,19377811110,
%U A162057 76372139937,305348766558,1238006401576,5086973436072
%N A162057 Number of nXn symmetric binary arrays with rows, considered as graycode 
               numbers, in nondecreasing order, and no more than 2 ones in any row 
               or column
%Y A162057 Sequence in context: A098407 A151390 A116426 this_sequence A026550 A124124 
               A052450
%Y A162057 Adjacent sequences: A162054 A162055 A162056 this_sequence A162058 A162059 
               A162060
%K A162057 nonn
%O A162057 1,1
%A A162057 Ron Hardin (rhhardin(AT)att.net) Jun 25 2009