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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 20 |
| 3 | 1662 |
| 4 | 353608 |
| 5 | 153356948 |
| 6 | 118150658380 |
| 7 | 147434290284772 |
| 8 | 278770751057930416 |
[1,20,1662,353608,153356948,118150658380, 147434290284772,278770751057930416] |