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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 3 |
| 4 | 0 |
| 5 | 0 |
| 6 | 90 |
| 7 | 63 |
| 8 | 0 |
| 9 | 8880 |
| 10 | 22680 |
| 11 | 49203 |
| 12 | 2118600 |
| 13 | 12383280 |
| 14 | 60540480 |
| 15 | 1131841623 |
| 16 | 10857974400 |
| 17 | 87893114400 |
| 18 | 1246674306240 |
| 19 | 15590737021923 |
| 20 | 175749917616000 |
| 21 | 2471071936993440 |
| 22 | 35757593223327360 |
| 23 | 502589340005210703 |
[1,0,0,3,0,0,90,63,0,8880,22680,49203,2118600, 12383280,60540480,1131841623,10857974400, 87893114400,1246674306240,15590737021923, 175749917616000,2471071936993440, 35757593223327360,502589340005210703] |