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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 6 |
| 3 | 6 |
| 4 | 48 |
| 5 | 384 |
| 6 | 1518 |
| 7 | 2037018 |
| 8 | 2037018 |
| 9 | 44279730804 |
| 10 | 424427587626 |
[2,6,6,48,384,1518,2037018,2037018,44279730804, 424427587626] |