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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 25 |
| 4 | 222 |
| 5 | 3166 |
| 6 | 47016 |
| 7 | 951544 |
| 8 | 19827408 |
| 9 | 520029520 |
| 10 | 13952218560 |
| 11 | 449559799360 |
| 12 | 14756761434240 |
| 13 | 563961412362880 |
| 14 | 21893890640563200 |
| 15 | 968019931702297600 |
| 16 | 43385863589508249600 |
| 17 | 2178487766250586470400 |
| 18 | 110704921777161066700800 |
| 19 | 6222745685273069016064000 |
[1,3,25,222,3166,47016,951544,19827408,520029520, 13952218560,449559799360,14756761434240, 563961412362880,21893890640563200, 968019931702297600,43385863589508249600, 2178487766250586470400,110704921777161066700800, 6222745685273069016064000] |