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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 12 |
| 4 | 120 |
| 5 | 1680 |
| 6 | 30480 |
| 7 | 678720 |
| 8 | 17902080 |
| 9 | 545529600 |
| 10 | 18854519040 |
| 11 | 728651911680 |
| 12 | 31133305082880 |
| 13 | 1457247407616000 |
| 14 | 74151941277173760 |
| 15 | 4075563460173004800 |
| 16 | 240617659203765043200 |
| 17 | 15186689706926068531200 |
| 18 | 1020415122190724766105600 |
| 19 | 72722026905140804154163200 |
[1,2,12,120,1680,30480,678720,17902080,545529600, 18854519040,728651911680,31133305082880, 1457247407616000,74151941277173760, 4075563460173004800,240617659203765043200, 15186689706926068531200,1020415122190724766105600, 72722026905140804154163200] |