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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 7 |
| 3 | 227 |
| 4 | 9130 |
| 5 | 408081 |
| 6 | 19274998 |
| 7 | 946866202 |
| 8 | 47865420384 |
| 9 | 2473743947058 |
[1,7,227,9130,408081,19274998,946866202, 47865420384,2473743947058] |