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| n | a(n) |
|---|---|
| 6 | 6 |
| 7 | 630 |
| 8 | 30240 |
| 9 | 1058400 |
| 10 | 31752000 |
| 11 | 880165440 |
| 12 | 23471078400 |
| 13 | 616475059200 |
| 14 | 16182470304000 |
| 15 | 428535787680000 |
| 16 | 11519041972838400 |
| 17 | 315583670578176000 |
| 18 | 8836342776188928000 |
| 19 | 253325921601392640000 |
| 20 | 7444680145020518400000 |
[6,630,30240,1058400,31752000,880165440, 23471078400,616475059200,16182470304000, 428535787680000,11519041972838400, 315583670578176000,8836342776188928000, 253325921601392640000,7444680145020518400000] |