221528

Appears in sequences

• Number of ways to place 4 nonattacking queens on a 4 X n board.at n=26A061990
• Number of (n+4) X 10 0..2 matrices with each 5 X 5 subblock idempotent.at n=13A224623
• Expansion of Sum_{k>=0} (k * x)^k/(1 + k^2 * x).at n=7A349884