| n | a(n) |
|---|---|
| 2 | 2 |
| 3 | 6 |
| 4 | 84 |
| 5 | 1020 |
| 6 | 15630 |
| 7 | 279930 |
| 8 | 5764808 |
| 9 | 134217720 |
| 10 | 3486784410 |
| 11 | 99999999990 |
| 12 | 3138428376732 |
| 13 | 106993205379060 |
| 14 | 3937376385699302 |
| 15 | 155568095557812210 |
| 16 | 6568408355712890640 |
| 17 | 295147905179352825840 |
| 18 | 14063084452067724991026 |
[2,6,84,1020,15630,279930,5764808,134217720, 3486784410,99999999990,3138428376732, 106993205379060,3937376385699302, 155568095557812210,6568408355712890640, 295147905179352825840,14063084452067724991026] |