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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 21 |
| 3 | 645 |
| 4 | 37961 |
| 5 | 1042405 |
| 6 | 323567035 |
| 7 | 30989984675 |
| 8 | 10042712381261 |
[3,21,645,37961,1042405,323567035,30989984675, 10042712381261] |