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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 28 |
| 4 | 217 |
| 5 | 1570 |
| 6 | 12515 |
| 7 | 102942 |
| 8 | 867677 |
| 9 | 7541800 |
| 10 | 66571277 |
| 11 | 595524791 |
[1,3,28,217,1570,12515,102942,867677,7541800, 66571277,595524791] |