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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 12 |
| 3 | 970 |
| 4 | 21801077 |
| 5 | 33006325301864331 |
| 6 | 216010416087275256441802643730702446 |
[1,2,12,970,21801077,33006325301864331, 216010416087275256441802643730702446] |