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| n | a(n) |
|---|---|
| 1 | 21 |
| 2 | 217 |
| 3 | 3937 |
| 4 | 1040257 |
| 5 | 1073602561 |
| 6 | 68718821377 |
| 7 | 1125897758834689 |
| 8 | 4951760154835678088235319297 |
| 9 | 1427247692705959880439315947500961989719490561 |
[21,217,3937,1040257,1073602561,68718821377, 1125897758834689,4951760154835678088235319297, 1427247692705959880439315947500961989719490561] |