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| n | a(n) |
|---|---|
| 2 | 6 |
| 3 | 90 |
| 4 | 1200 |
| 5 | 15750 |
| 6 | 211680 |
| 7 | 2963520 |
| 8 | 43545600 |
| 9 | 673596000 |
| 10 | 10977120000 |
| 11 | 188367379200 |
| 12 | 3399953356800 |
| 13 | 64457449056000 |
| 14 | 1281520880640000 |
| 15 | 26676557107200000 |
| 16 | 580481882652672000 |
| 17 | 13183287756807168000 |
[6,90,1200,15750,211680,2963520,43545600, 673596000,10977120000,188367379200,3399953356800, 64457449056000,1281520880640000,26676557107200000, 580481882652672000,13183287756807168000] |