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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 720 |
| 7 | 5040 |
| 8 | 35280 |
| 9 | 246960 |
| 10 | 1573200 |
| 11 | 9376680 |
| 12 | 53715384 |
| 13 | 302432574 |
| 14 | 1701740006 |
| 15 | 9682617631 |
| 16 | 56153444761 |
| 17 | 329186004844 |
| 18 | 1939175437540 |
| 19 | 11433268461744 |
| 20 | 67308307316544 |
| 21 | 395239738691520 |
| 22 | 2315040687288576 |
[1,2,6,24,120,720,5040,35280,246960,1573200, 9376680,53715384,302432574,1701740006,9682617631, 56153444761,329186004844,1939175437540, 11433268461744,67308307316544,395239738691520, 2315040687288576] |