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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 7 |
| 4 | 72 |
| 5 | 883 |
| 6 | 16968 |
| 7 | 409199 |
| 8 | 12099880 |
| 9 | 420661470 |
| 10 | 16838275108 |
| 11 | 762821788869 |
[1,3,7,72,883,16968,409199,12099880,420661470, 16838275108,762821788869] |