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| n | a(n) |
|---|---|
| 1 | 6 |
| 2 | 24 |
| 3 | 216 |
| 4 | 1536 |
| 5 | 11616 |
| 6 | 86400 |
| 7 | 645504 |
| 8 | 4816896 |
| 9 | 35956224 |
| 10 | 268376064 |
| 11 | 2003195904 |
| 12 | 14952038400 |
| 13 | 111603572736 |
| 14 | 833020329984 |
| 15 | 6217748545536 |
| 16 | 46409906651136 |
| 17 | 346408259813376 |
| 18 | 2585626450329600 |
| 19 | 19299378566529024 |
| 20 | 144052522724622336 |
[6,24,216,1536,11616,86400,645504,4816896, 35956224,268376064,2003195904,14952038400, 111603572736,833020329984,6217748545536, 46409906651136,346408259813376,2585626450329600, 19299378566529024,144052522724622336] |