Number of 2n X 2n symmetric matrices with entries in {+1, -1} and all rows and columns summing to zero.
A333164
Number of 2n X 2n symmetric matrices with entries in {+1, -1} and all rows and columns summing to zero.
Terms
- a(0) =1a(1) =2a(2) =18a(3) =1760a(4) =1944530a(5) =26615510712
External references
- oeis: A333164