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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 18 |
| 5 | 16666 |
| 6 | 262134 |
| 7 | 4048124214 |
| 8 | 24430928839 |
| 9 | 243293052886 |
| 10 | 41293676570106 |
| 11 | 3935632929857549 |
[1,2,6,18,16666,262134,4048124214,24430928839, 243293052886,41293676570106,3935632929857549] |