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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 2 |
| 4 | 4 |
| 5 | 12 |
| 6 | 72 |
| 7 | 648 |
| 8 | 11664 |
| 9 | 349920 |
| 10 | 19595520 |
| 11 | 1939956480 |
| 12 | 360831905280 |
| 13 | 120878688268800 |
| 14 | 76153573609344000 |
| 15 | 88414298960448384000 |
| 16 | 192920000331698373888000 |
| 17 | 787113601353329365463040000 |
| 18 | 6068645866434169407720038400000 |
| 19 | 88189561731021349832987598028800000 |
| 20 | 2433502766405803127291459780006707200000 |
[1,1,2,2,4,12,72,648,11664,349920,19595520, 1939956480,360831905280,120878688268800, 76153573609344000,88414298960448384000, 192920000331698373888000, 787113601353329365463040000, 6068645866434169407720038400000, 88189561731021349832987598028800000, 2433502766405803127291459780006707200000] |