Number of n X n symmetric matrices whose first row is 1..n and whose rows and columns are all permutations of 1..n.
A035481
Number of n X n symmetric matrices whose first row is 1..n and whose rows and columns are all permutations of 1..n.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =4a(5) =6a(6) =456a(7) =6240a(8) =10936320a(9) =1225566720
External references
- oeis: A035481