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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 7 |
| 3 | 334 |
| 4 | 58875 |
| 5 | 33405756 |
| 6 | 68716991862 |
| 7 | 562949918300022 |
| 8 | 18446744073262895647 |
| 9 | 2417851639229253060330052 |
[2,7,334,58875,33405756,68716991862, 562949918300022,18446744073262895647, 2417851639229253060330052] |