The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 9 |
| 3 | 90 |
| 4 | 2376 |
| 5 | 126540 |
| 6 | 14362920 |
| 7 | 3403449396 |
| 8 | 1709255996280 |
| 9 | 1815331983698400 |
| 10 | 4087173374510731764 |
| 11 | 19501827096038985616536 |
[1,9,90,2376,126540,14362920,3403449396, 1709255996280,1815331983698400, 4087173374510731764,19501827096038985616536] |