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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 17 |
| 5 | 73 |
| 6 | 521 |
| 7 | 7411 |
| 8 | 207693 |
| 9 | 7583663 |
| 10 | 399906057 |
| 11 | 35432211775 |
[1,1,1,17,73,521,7411,207693,7583663,399906057, 35432211775] |