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| n | a(n) |
|---|---|
| 1 | 21 |
| 2 | 161 |
| 3 | 1071 |
| 4 | 6797 |
| 5 | 42231 |
| 6 | 259421 |
| 7 | 1582791 |
| 8 | 9614717 |
| 9 | 58230711 |
| 10 | 351922781 |
| 11 | 2123580711 |
| 12 | 12799240637 |
| 13 | 77074749591 |
| 14 | 463808234141 |
| 15 | 2789504205831 |
| 16 | 16769733474557 |
| 17 | 100779708074871 |
| 18 | 605475935585501 |
| 19 | 3636808913042151 |
| 20 | 21840480209276477 |
| 21 | 131140458175102551 |
| 22 | 787328413691288861 |
[21,161,1071,6797,42231,259421,1582791,9614717, 58230711,351922781,2123580711,12799240637, 77074749591,463808234141,2789504205831, 16769733474557,100779708074871,605475935585501, 3636808913042151,21840480209276477, 131140458175102551,787328413691288861] |