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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 7 |
| 3 | 24 |
| 4 | 208 |
| 5 | 2539 |
| 6 | 54394 |
| 7 | 1993507 |
| 8 | 127100730 |
| 9 | 14090201105 |
| 10 | 2730583715609 |
[1,7,24,208,2539,54394,1993507,127100730, 14090201105,2730583715609] |