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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 3 |
| 3 | 12 |
| 4 | 30 |
| 5 | 240 |
| 6 | 840 |
| 7 | 10080 |
| 8 | 45360 |
| 9 | 725760 |
| 10 | 3991680 |
| 11 | 79833600 |
| 12 | 518918400 |
| 13 | 12454041600 |
| 14 | 93405312000 |
| 15 | 2615348736000 |
| 16 | 22230464256000 |
| 17 | 711374856192000 |
| 18 | 6758061133824000 |
| 19 | 243290200817664000 |
| 20 | 2554547108585472000 |
| 21 | 102181884343418880000 |
| 22 | 1175091669949317120000 |
[2,3,12,30,240,840,10080,45360,725760,3991680, 79833600,518918400,12454041600,93405312000, 2615348736000,22230464256000,711374856192000, 6758061133824000,243290200817664000, 2554547108585472000,102181884343418880000, 1175091669949317120000] |