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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 15 |
| 3 | 504 |
| 4 | 17280 |
| 5 | 1108800 |
| 6 | 59304960 |
| 7 | 5613753600 |
| 8 | 944393748480 |
| 9 | 83547459072000 |
| 10 | 18057977118720000 |
| 11 | 2985679725841612800 |
| 12 | 366843845931171840000 |
| 13 | 71218197373471948800000 |
| 14 | 22048551163610844364800000 |
| 15 | 7384118713322835982417920000 |
[1,15,504,17280,1108800,59304960,5613753600, 944393748480,83547459072000,18057977118720000, 2985679725841612800,366843845931171840000, 71218197373471948800000, 22048551163610844364800000, 7384118713322835982417920000] |