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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 24 |
| 4 | 12 |
| 5 | 640 |
| 6 | 1920 |
| 7 | 107520 |
| 8 | 1792 |
| 9 | 2064384 |
| 10 | 10321920 |
| 11 | 43253760 |
| 12 | 64880640 |
| 13 | 5398069248 |
| 14 | 4198498304 |
| 15 | 503819796480 |
| 16 | 62977474560 |
| 17 | 16610786017280 |
| 18 | 4271344975872 |
| 19 | 649244436332544 |
| 20 | 41618233098240 |
| 21 | 27967452642017280 |
[1,1,24,12,640,1920,107520,1792,2064384,10321920, 43253760,64880640,5398069248,4198498304, 503819796480,62977474560,16610786017280, 4271344975872,649244436332544,41618233098240, 27967452642017280] |