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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 | 1728720 |
| 11 | 11167920 |
| 12 | 68286120 |
| 13 | 404423736 |
| 14 | 2363607402 |
| 15 | 13821281314 |
| 16 | 81653389147 |
| 17 | 490572457453 |
| 18 | 2976080502144 |
| 19 | 18138009463432 |
| 20 | 110672621450160 |
| 21 | 674657720355264 |
| 22 | 4104712985389632 |
[1,2,6,24,120,720,5040,35280,246960,1728720, 11167920,68286120,404423736,2363607402, 13821281314,81653389147,490572457453, 2976080502144,18138009463432,110672621450160, 674657720355264,4104712985389632] |