Number of ways to place 2n rooks on n X n board, 2 rooks in each row and each column, multiple rooks in a cell allowed, and exactly 3 rooks below the main diagonal.
A260575
Number of ways to place 2n rooks on n X n board, 2 rooks in each row and each column, multiple rooks in a cell allowed, and exactly 3 rooks below the main diagonal.
Terms
- a(0) =4a(1) =114a(2) =1492a(3) =13992a(4) =109538a(5) =769632a(6) =5050616a(7) =31702275a(8) =193204684a(9) =1154354559a(10) =6805263818a(11) =39756392269a(12) =230829718918
External references
- oeis: A260575