The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 1 |
| 4 | 27 |
| 5 | 555 |
| 6 | 24981 |
| 7 | 1825761 |
| 8 | 184975696 |
| 9 | 24714858112 |
| 10 | 4188322485532 |
| 11 | 875632389820566 |
[1,0,1,27,555,24981,1825761,184975696,24714858112, 4188322485532,875632389820566] |