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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 9 |
| 3 | 48 |
| 4 | 297 |
| 5 | 2040 |
| 6 | 15425 |
| 7 | 125232 |
| 8 | 1070553 |
| 9 | 9530752 |
| 10 | 86526701 |
| 11 | 800164636 |
| 12 | 7368225813 |
| 13 | 68065405520 |
| 14 | 586441789081 |
[2,9,48,297,2040,15425,125232,1070553,9530752, 86526701,800164636,7368225813,68065405520, 586441789081] |