The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 21 |
| 4 | 945 |
| 5 | 1845585 |
| 6 | 6922244887425 |
| 7 | 96595543392827888368850625 |
| 8 | 18734868077603955570406193129480504943860234712890625 |
[1,1,3,21,945,1845585,6922244887425, 96595543392827888368850625, 18734868077603955570406193129480504943860234712890\ 625] |