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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 13 |
| 5 | 289 |
| 6 | 1645423 |
| 7 | 7499988983197 |
| 8 | 1716234423353399580977511919 |
| 9 | 12985299047930678223817284541389710796223289877600061663 |
[1,1,3,13,289,1645423,7499988983197, 1716234423353399580977511919, 12985299047930678223817284541389710796223289877600\ 061663] |