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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 24 |
| 5 | 96 |
| 6 | 336 |
| 7 | 672 |
| 8 | 3024 |
| 9 | 9072 |
| 10 | 35280 |
| 11 | 120960 |
| 12 | 483840 |
| 13 | 1874880 |
| 14 | 10108800 |
| 15 | 20217600 |
| 16 | 107827200 |
| 17 | 398131200 |
| 18 | 1919877120 |
| 19 | 6051594240 |
| 20 | 24710676480 |
| 21 | 86487367680 |
| 22 | 339771801600 |
| 23 | 1141066967040 |
| 24 | 4122564526080 |
| 25 | 16784726999040 |
[1,1,3,6,24,96,336,672,3024,9072,35280,120960, 483840,1874880,10108800,20217600,107827200, 398131200,1919877120,6051594240,24710676480, 86487367680,339771801600,1141066967040, 4122564526080,16784726999040] |