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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 20 |
| 3 | 175 |
| 4 | 2076 |
| 5 | 32208 |
| 6 | 626028 |
| 7 | 14688924 |
| 8 | 404166432 |
| 9 | 12756813408 |
| 10 | 454171720320 |
| 11 | 18000130993920 |
| 12 | 785833199683200 |
| 13 | 37465916611881600 |
| 14 | 1936722997186387200 |
| 15 | 107888448215162361600 |
| 16 | 6442944965583133593600 |
| 17 | 410602312459198056960000 |
[3,20,175,2076,32208,626028,14688924,404166432, 12756813408,454171720320,18000130993920, 785833199683200,37465916611881600, 1936722997186387200,107888448215162361600, 6442944965583133593600,410602312459198056960000] |