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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 21 |
| 3 | 189 |
| 4 | 1703 |
| 5 | 15330 |
| 6 | 137970 |
| 7 | 1241732 |
| 8 | 11175591 |
| 9 | 100580319 |
| 10 | 905222873 |
| 11 | 8147005860 |
| 12 | 73323052740 |
| 13 | 659907474662 |
| 14 | 5939167271961 |
| 15 | 53452505447649 |
| 16 | 481072549028843 |
| 17 | 4329652941259590 |
[2,21,189,1703,15330,137970,1241732,11175591, 100580319,905222873,8147005860,73323052740, 659907474662,5939167271961,53452505447649, 481072549028843,4329652941259590] |