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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 48 |
| 4 | 1 |
| 5 | 3840 |
| 6 | 92160 |
| 7 | 645120 |
| 8 | 3440640 |
| 9 | 30965760 |
| 10 | 14863564800 |
| 11 | 24222105600 |
| 12 | 7847962214400 |
| 13 | 40809403514880 |
| 14 | 5713316492083200 |
| 15 | 7617755322777600 |
| 16 | 5484783832399872000 |
| 17 | 5328075722902732800 |
| 18 | 1220613711064989696000 |
[1,1,4,48,1,3840,92160,645120,3440640,30965760, 14863564800,24222105600,7847962214400, 40809403514880,5713316492083200,7617755322777600, 5484783832399872000,5328075722902732800, 1220613711064989696000] |