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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 7 |
| 3 | 51 |
| 4 | 1165 |
| 5 | 80519 |
| 6 | 12594359 |
| 7 | 5423217685 |
| 8 | 5925057763939 |
| 9 | 16185578398527540 |
[1,7,51,1165,80519,12594359,5423217685, 5925057763939,16185578398527540] |