The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 1 |
| 4 | 3 |
| 5 | 21 |
| 6 | 632 |
| 7 | 58741 |
| 8 | 16972746 |
| 9 | 14821714373 |
| 10 | 39880712826780 |
[1,0,1,3,21,632,58741,16972746,14821714373, 39880712826780] |