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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 60 |
| 7 | 360 |
| 8 | 6030 |
| 9 | 35280 |
| 10 | 410976 |
| 11 | 1174896 |
| 12 | 19948200 |
| 13 | 43022700 |
| 14 | 543757860 |
| 15 | 2524673904 |
| 16 | 15399118440 |
| 17 | 46338868800 |
| 18 | 737917466160 |
| 19 | 1459120076400 |
| 20 | 19381180990752 |
| 21 | 75959665269840 |
| 22 | 534453892557660 |
[0,0,0,0,0,60,360,6030,35280,410976,1174896, 19948200,43022700,543757860,2524673904, 15399118440,46338868800,737917466160, 1459120076400,19381180990752,75959665269840, 534453892557660] |