%I A005312 M2659
%S A005312 1,3,7,16,46,138
%N A005312 Number of symmetric anti-Hadamard matrices of order n.
%D A005312 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A005312 R. L. Graham and N. J. A. Sloane, Anti-Hadamard matrices, Linear Alg. 
               Applic., 62 (1984), 113-137.
%Y A005312 Sequence in context: A058300 A000674 A129045 this_sequence A143817 A000963 
               A133593
%Y A005312 Adjacent sequences: A005309 A005310 A005311 this_sequence A005313 A005314 
               A005315
%K A005312 nonn
%O A005312 1,2
%A A005312 N. J. A. Sloane (njas(AT)research.att.com).