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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 7 |
| 2 | 51 |
| 3 | 385 |
| 4 | 2993 |
| 5 | 23807 |
| 6 | 192627 |
| 7 | 1577849 |
| 8 | 13036417 |
| 9 | 108350935 |
| 10 | 904201491 |
| 11 | 7566326929 |
| 12 | 63431106929 |
| 13 | 532418131343 |
| 14 | 4472591813139 |
| 15 | 37592633210825 |
| 16 | 316085049734017 |
| 17 | 2658336935367463 |
| 18 | 22360719757645683 |
| 19 | 188108240644768801 |
[1,7,51,385,2993,23807,192627,1577849,13036417, 108350935,904201491,7566326929,63431106929, 532418131343,4472591813139,37592633210825, 316085049734017,2658336935367463, 22360719757645683,188108240644768801] |