%I #3 Mar 31 2012 14:09:57
%S 1,3,73,12787,13698241
%N Number of n X n {0,1,1}matrices A such that permanent( A ) =  det A , where A is obtained from A by taking the absolute value of each entry.
%C Also the number of n X n signnonsingular matrices (see reference for definition).
%D Brualdi, Richard A. and Shader, Bryan L., On signnonsingular matrices and the conversion of the permanent into the determinant, in Applied Geometry and Discrete Mathematics (The Victor Klee Festschrift), pp. 117134, DIMACS Ser. Discrete Math. Theoret. Comput. Sci., 4, Amer. Math. Soc., Providence, RI, 1991.
%Y Cf. A145676.
%K nonn
%O 0,2
%A _N. J. A. Sloane_, Mar 26 2009
%E a(1)a(4) computed by _Eric W. Weisstein_, Mar 26, 2009
