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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 7 |
| 3 | 43 |
| 4 | 309 |
| 5 | 1565 |
| 6 | 8281 |
| 7 | 43977 |
| 8 | 233983 |
| 9 | 1246261 |
| 10 | 6642635 |
| 11 | 35404681 |
| 12 | 188678871 |
| 13 | 1005542727 |
| 14 | 5358879227 |
| 15 | 28558908161 |
| 16 | 152197318255 |
| 17 | 811095694201 |
| 18 | 4322522046735 |
| 19 | 23035759794981 |
| 20 | 122763158514755 |
| 21 | 654234809106745 |
[1,7,43,309,1565,8281,43977,233983,1246261, 6642635,35404681,188678871,1005542727,5358879227, 28558908161,152197318255,811095694201, 4322522046735,23035759794981,122763158514755, 654234809106745] |