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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 7 |
| 3 | 51 |
| 4 | 391 |
| 5 | 2894 |
| 6 | 22491 |
| 7 | 173099 |
| 8 | 1351439 |
| 9 | 10562301 |
| 10 | 83067164 |
| 11 | 654664840 |
| 12 | 5177288283 |
| 13 | 41027782738 |
| 14 | 325853413087 |
| 15 | 2592430133475 |
| 16 | 20658531950143 |
| 17 | 164850585115958 |
| 18 | 1317141294092889 |
| 19 | 10535656551412625 |
| 20 | 84359922128250860 |
[1,7,51,391,2894,22491,173099,1351439,10562301, 83067164,654664840,5177288283,41027782738, 325853413087,2592430133475,20658531950143, 164850585115958,1317141294092889, 10535656551412625,84359922128250860] |