%I #23 May 27 2024 06:50:42
%S 0,1,33,7875,15099201,237634987683,30805715676309201
%N Number of singular n X n (-1,0,1)-matrices.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/SingularMatrix.html">Singular Matrix.</a>
%H Minfeng Wang, <a href="/A057981/a057981.cpp.txt">C++ program to calculate A057981</a>
%F a(n) = A060722(n) - A056989(n). - _Alois P. Heinz_, Dec 02 2019
%Y Complement of A056989.
%Y Cf. A060722, A330134.
%K nonn,more
%O 0,3
%A _Eric W. Weisstein_, Oct 23 2000
%E a(5) from _Giovanni Resta_, Feb 20 2009
%E a(0)=0 prepended by _Alois P. Heinz_, Dec 02 2019
%E a(0)-a(5) confirmed and a(6) added by _Minfeng Wang_, May 01 2024