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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 84 |
| 4 | 45444 |
| 5 | 15686405364 |
| 6 | 2147492192737717340004 |
| 7 | 45388476229808808857318702720533556450342484 |
[1,4,84,45444,15686405364,2147492192737717340004, 45388476229808808857318702720533556450342484] |