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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 52 |
| 3 | 226 |
| 4 | 1013 |
| 5 | 5294 |
| 6 | 27639 |
| 7 | 139226 |
| 8 | 713421 |
| 9 | 3674765 |
| 10 | 18853673 |
| 11 | 96786807 |
| 12 | 497418193 |
| 13 | 2555599511 |
| 14 | 13129374671 |
| 15 | 67461650707 |
| 16 | 346631157067 |
| 17 | 1781036709459 |
| 18 | 9151338992559 |
| 19 | 47021631140929 |
| 20 | 241607368725137 |
| 21 | 1241433013500699 |
[2,52,226,1013,5294,27639,139226,713421,3674765, 18853673,96786807,497418193,2555599511, 13129374671,67461650707,346631157067, 1781036709459,9151338992559,47021631140929, 241607368725137,1241433013500699] |