3110940

Appears in sequences

• Number of n X n matrices with exactly 2 1's in each row and column, other entries 0.at n=7A001499
• Triangle read by rows: T(n,k) (n >= 0, 0 <= k <= n) gives number of {0,1} n X n matrices with all row and column sums equal to k.at n=30A008300
• Triangle read by rows: T(n,k) (n >= 0, 0 <= k <= n) gives number of {0,1} n X n matrices with all row and column sums equal to k.at n=33A008300
• Number of n X n (0,1) matrices containing exactly five 1's in each row and in each column.at n=2A075754
• Number of 7*n X 7 0..1 arrays with row sums 2 and column sums 2*n.at n=0A172606
• Triangle read by rows: T(n, k) is the number of ways to place k points on an n X n square grid so that no more than 2 points are on a vertical or horizontal straight line.at n=44A279445