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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 48 |
| 5 | 400 |
| 6 | 10800 |
| 7 | 246960 |
| 8 | 21073920 |
| 9 | 1316818944 |
| 10 | 342921600000 |
| 11 | 58442186880000 |
| 12 | 45444644517888000 |
| 13 | 21101743065006489600 |
| 14 | 48272757747179554068480 |
| 15 | 61034174848925197920000000 |
| 16 | 406342672548486275137536000000 |
| 17 | 1398378373047164966922973347840000 |
[1,1,2,6,48,400,10800,246960,21073920,1316818944, 342921600000,58442186880000,45444644517888000, 21101743065006489600,48272757747179554068480, 61034174848925197920000000, 406342672548486275137536000000, 1398378373047164966922973347840000] |