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| n | a(n) |
|---|---|
| 8 | 1 |
| 9 | 36 |
| 10 | 990 |
| 11 | 26070 |
| 12 | 705375 |
| 13 | 20151846 |
| 14 | 614506893 |
| 15 | 20073049425 |
| 16 | 702495121185 |
| 17 | 26300384653400 |
| 18 | 1050925859466912 |
| 19 | 44702294310795888 |
| 20 | 2018603140944000000 |
| 21 | 96508616036970572820 |
| 22 | 4872478522317533107200 |
| 23 | 259140537891648535707618 |
| 24 | 14485018396686799073181696 |
[1,36,990,26070,705375,20151846,614506893, 20073049425,702495121185,26300384653400, 1050925859466912,44702294310795888, 2018603140944000000,96508616036970572820, 4872478522317533107200,259140537891648535707618, 14485018396686799073181696] |