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| n | a(n) |
|---|---|
| 2 | 20 |
| 3 | 491 |
| 4 | 7502 |
| 5 | 52013 |
| 6 | 297464 |
| 7 | 1119791 |
| 8 | 3900890 |
| 9 | 11135201 |
| 10 | 29329232 |
[20,491,7502,52013,297464,1119791,3900890, 11135201,29329232] |