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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 5 |
| 3 | 66 |
| 4 | 852 |
| 5 | 34159 |
| 6 | 6379211 |
| 7 | 2703029494 |
| 8 | 2266768029479 |
| 9 | 5448033721050367 |
[1,5,66,852,34159,6379211,2703029494, 2266768029479,5448033721050367] |