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| n | a(n) |
|---|---|
| 1 | 9 |
| 2 | 624 |
| 3 | 19040 |
| 4 | 30222192 |
| 5 | 592704000 |
| 6 | 12040481088 |
| 7 | 128024064000 |
| 8 | 1024192512000 |
| 9 | 3456649728000 |
[9,624,19040,30222192,592704000,12040481088, 128024064000,1024192512000,3456649728000] |