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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 18 |
| 3 | 84 |
| 4 | 15210 |
| 5 | 15216 |
| 6 | 66720 |
| 7 | 2858880 |
| 8 | 62905344 |
| 9 | 358313760 |
| 10 | 3633603510 |
[2,18,84,15210,15216,66720,2858880,62905344, 358313760,3633603510] |