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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 3 |
| 4 | 8 |
| 5 | 25 |
| 6 | 108 |
| 7 | 735 |
| 8 | 4608 |
| 9 | 40824 |
| 10 | 362000 |
| 11 | 3628185 |
| 12 | 40766976 |
| 13 | 478988081 |
| 14 | 6227101888 |
| 15 | 87146087625 |
| 16 | 1300561920000 |
| 17 | 20922788404479 |
| 18 | 355737629952000 |
| 19 | 6402373698206889 |
| 20 | 121810906419200000 |
| 21 | 2432822933484213543 |
| 22 | 51090942172652090368 |
| 23 | 1124000727778962143055 |
[1,3,8,25,108,735,4608,40824,362000,3628185, 40766976,478988081,6227101888,87146087625, 1300561920000,20922788404479,355737629952000, 6402373698206889,121810906419200000, 2432822933484213543,51090942172652090368, 1124000727778962143055] |