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| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 3 |
| 2 | 6 |
| 3 | 20 |
| 4 | 168 |
| 5 | 7581 |
| 6 | 7828354 |
| 7 | 2414682040998 |
| 8 | 56130437228687557907788 |
| 9 | 286386577668298411128469151667598498812366 |
[2,3,6,20,168,7581,7828354,2414682040998, 56130437228687557907788, 286386577668298411128469151667598498812366] |