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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 24 |
| 4 | 552 |
| 5 | 27204 |
| 6 | 2812168 |
| 7 | 611509240 |
| 8 | 279902590168 |
| 9 | 269562004096692 |
| 10 | 546187771866465456 |
| 11 | 2328406266027562097220 |
| 12 | 20883572160878878738558896 |
| 13 | 394075725737300936910238275696 |
[1,2,24,552,27204,2812168,611509240,279902590168, 269562004096692,546187771866465456, 2328406266027562097220,20883572160878878738558896, 394075725737300936910238275696] |