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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 480 |
| 7 | 3600 |
| 8 | 23040 |
| 9 | 221760 |
| 10 | 1895040 |
| 11 | 17942400 |
| 12 | 195229440 |
| 13 | 2726760960 |
| 14 | 29650279680 |
| 15 | 479288355840 |
| 16 | 6120338273280 |
| 17 | 99262251970560 |
| 18 | 1726003206789120 |
[1,2,6,24,120,480,3600,23040,221760,1895040, 17942400,195229440,2726760960,29650279680, 479288355840,6120338273280,99262251970560, 1726003206789120] |