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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 680 |
| 3 | 9509536 |
| 4 | 4062408076312 |
| 5 | 83625724607330716008 |
| 6 | 81642366196089406720417732740 |
[1,680,9509536,4062408076312,83625724607330716008, 81642366196089406720417732740] |