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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 40 |
| 4 | 1728 |
| 5 | 10560 |
| 6 | 604800 |
| 7 | 4386816 |
| 8 | 348364800 |
| 9 | 76859228160 |
| 10 | 490311843840 |
| 11 | 172454510592000 |
| 12 | 6951148594790400 |
| 13 | 54188395462656000 |
| 14 | 5673488083845120000 |
| 15 | 2112698895984230400000 |
| 16 | 458667310457770160947200 |
[1,6,40,1728,10560,604800,4386816,348364800, 76859228160,490311843840,172454510592000, 6951148594790400,54188395462656000, 5673488083845120000,2112698895984230400000, 458667310457770160947200] |