The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 91 |
| 4 | 597871 |
| 5 | 213122969971321411 |
| 6 | 9680343693975641657052402556458789711774336036960631 |
[1,6,91,597871,213122969971321411, 96803436939756416570524025564587897117743360369606\ 31] |