A086906 Number of symmetric singular n X n (0,1) matrices over the reals.

1, 4, 32, 496, 14172, 816684, 87982904, 18748545824, 7565600671504, 5940152086634096

Offset: 1

Author

Yuval Dekel (dekelyuval(AT)hotmail.com), Sep 19 2003

Keywords

• nonn
• more

Crossrefs

Cf. A046747, A086899, A086879, A086900, A118989, A118990, A118991, A118996, A119008, A119010.

Cf. A006125.

Formula

a(n) = 2^(n*(n+1)/2) - A086899(n).

Extensions

W. Edwin Clark computed the first entries.

a(6)-a(7) from Giovanni Resta, May 08 2006

a(8)-a(10) from Max Alekseyev, Jun 17 2025