The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 9 |
| 4 | 53 |
| 5 | 418 |
| 6 | 2894 |
| 7 | 33675 |
| 8 | 369763 |
| 9 | 4769542 |
| 10 | 58853842 |
| 11 | 139505110 |
| 12 | 21847262156 |
[1,1,2,9,53,418,2894,33675,369763,4769542, 58853842,139505110,21847262156] |