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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 5 |
| 4 | 21 |
| 5 | 108 |
| 6 | 660 |
| 7 | 4680 |
| 8 | 37800 |
| 9 | 342720 |
| 10 | 3447360 |
| 11 | 38102400 |
| 12 | 459043200 |
| 13 | 5987520000 |
| 14 | 84064780800 |
| 15 | 1264085222400 |
| 16 | 20268952704000 |
| 17 | 345226033152000 |
| 18 | 6224529991680000 |
| 19 | 118443913555968000 |
| 20 | 2372079457972224000 |
[1,3,5,21,108,660,4680,37800,342720,3447360, 38102400,459043200,5987520000,84064780800, 1264085222400,20268952704000,345226033152000, 6224529991680000,118443913555968000, 2372079457972224000] |