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| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 4 |
| 2 | 17 |
| 3 | 102 |
| 4 | 925 |
| 5 | 12508 |
| 6 | 274369 |
| 7 | 8955595 |
| 8 | 447311286 |
| 9 | 34069625935 |
| 10 | 3993234239468 |
[2,4,17,102,925,12508,274369,8955595,447311286, 34069625935,3993234239468] |