%I A027832
%S A027832 1,5,14,315,2634,301262,8035168,4451407563,392447922178,1028823851939030,
               306635655405986312,3743721825782942609558,
%T A027832 3832881704712490758507152,215313862348697780762374273824,
%U A027832 766493362781127793638943080523776,196222469681558506008588371784165178651,
               2452358136558134202145977229121349160510450
%N A027832 Number of symmetric {-1, +1} matrices of order n with nonnegative row 
               and column sums.
%D A027832 I. Anderson, Combinatorics of Finite Sets, Oxford 1987, Ch. 3.1.
%D A027832 C. Greene and D. J. Kleitman, Strong versions of Sperner's Theorem, J. 
               Combin. Theory, A 20 (1976) 80-88.
%D A027832 Torsten Sillke and Achim Flammenkamp, unpublished.
%e A027832 n=2: A(2) = 5 from ++/++, ++/+-, -+/++, -+/+-, +-/-+
%Y A027832 Sequence in context: A027304 A070135 A067857 this_sequence A128946 A156219 
               A000331
%Y A027832 Adjacent sequences: A027829 A027830 A027831 this_sequence A027833 A027834 
               A027835
%K A027832 nonn,nice
%O A027832 1,2
%A A027832 Torsten Sillke (sillke(AT)Mathematik.Uni-Bielefeld.DE)