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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 24 |
| 5 | 120 |
| 6 | 660 |
| 7 | 4200 |
| 8 | 30688 |
| 9 | 254016 |
| 10 | 2352240 |
| 11 | 24108480 |
| 12 | 271016064 |
| 13 | 3316135680 |
| 14 | 43877957760 |
| 15 | 624306009600 |
| 16 | 9505324339200 |
| 17 | 154205312163840 |
| 18 | 2655567756979200 |
| 19 | 48382249157222400 |
| 20 | 929788248840192000 |
| 21 | 18796669969158144000 |
| 22 | 398766195659497881600 |
[0,0,0,0,24,120,660,4200,30688,254016,2352240, 24108480,271016064,3316135680,43877957760, 624306009600,9505324339200,154205312163840, 2655567756979200,48382249157222400, 929788248840192000,18796669969158144000, 398766195659497881600] |