The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 18 |
| 3 | 2180 |
| 4 | 2200776 |
| 5 | 20355006224 |
| 6 | 1801272981919008 |
| 7 | 1560858753560238398528 |
| 8 | 13428038397958481723104394368 |
| 9 | 1157111379933346772804754279450353920 |
| 10 | 1004777133003025735713513459537724394989392384 |
[1,18,2180,2200776,20355006224,1801272981919008, 1560858753560238398528, 13428038397958481723104394368, 1157111379933346772804754279450353920, 1004777133003025735713513459537724394989392384] |