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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 8 |
| 3 | 48 |
| 4 | 384 |
| 5 | 3840 |
| 6 | 46080 |
| 7 | 645120 |
| 8 | 10321920 |
| 9 | 185794560 |
| 10 | 3715891200 |
| 11 | 81749606400 |
| 12 | 1961990553600 |
| 13 | 51011754393600 |
| 14 | 1428329123020800 |
| 15 | 42849873690624000 |
| 16 | 1371195958099968000 |
| 17 | 46620662575398912000 |
| 18 | 1678343852714360832000 |
| 19 | 63777066403145711616000 |
[1,2,8,48,384,3840,46080,645120,10321920, 185794560,3715891200,81749606400,1961990553600, 51011754393600,1428329123020800,42849873690624000, 1371195958099968000,46620662575398912000, 1678343852714360832000,63777066403145711616000] |