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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 48 |
| 4 | 828 |
| 5 | 8820 |
| 6 | 26100 |
| 7 | 417600 |
| 8 | 2114100 |
| 9 | 3009600 |
| 10 | 43864128 |
| 11 | 200278848 |
| 12 | 1013911668 |
| 13 | 7823392500 |
| 14 | 16222586688 |
| 15 | 259561387008 |
| 16 | 633694792500 |
| 17 | 4152982192128 |
[1,3,48,828,8820,26100,417600,2114100,3009600, 43864128,200278848,1013911668,7823392500, 16222586688,259561387008,633694792500, 4152982192128] |