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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 120 |
| 3 | 1680 |
| 4 | 8960 |
| 5 | 25344 |
| 6 | 30750720 |
| 7 | 53248 |
| 8 | 167116800 |
| 9 | 1333592064 |
| 10 | 2739404800 |
| 11 | 72351744 |
| 12 | 526720696320 |
| 13 | 419430400 |
| 14 | 525462405120 |
| 15 | 55745722712064 |
| 16 | 45268955299840 |
| 17 | 141733920768 |
| 18 | 3462000479620300800 |
| 19 | 2542620639232 |
| 20 | 483482750523801600 |
| 21 | 284950532966055936 |
[1,120,1680,8960,25344,30750720,53248,167116800, 1333592064,2739404800,72351744,526720696320, 419430400,525462405120,55745722712064, 45268955299840,141733920768,3462000479620300800, 2542620639232,483482750523801600, 284950532966055936] |