Number of symmetric {-1, +1} matrices of order n with nonnegative row and column sums.
A027832
Number of symmetric {-1, +1} matrices of order n with nonnegative row and column sums.
Terms
- a(0) =1a(1) =5a(2) =14a(3) =315a(4) =2634a(5) =301262a(6) =8035168a(7) =4451407563a(8) =392447922178
External references
- oeis: A027832