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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 7 |
| 2 | 43 |
| 3 | 247 |
| 4 | 1527 |
| 5 | 9497 |
| 6 | 59245 |
| 7 | 369803 |
| 8 | 2308687 |
| 9 | 14413783 |
| 10 | 89990323 |
| 11 | 561842893 |
| 12 | 3507795765 |
| 13 | 21900487967 |
| 14 | 136732988323 |
| 15 | 853675514807 |
| 16 | 5329817595487 |
| 17 | 33276057627697 |
| 18 | 207754954396765 |
| 19 | 1297092388823683 |
| 20 | 8098236068810727 |
[1,7,43,247,1527,9497,59245,369803,2308687, 14413783,89990323,561842893,3507795765, 21900487967,136732988323,853675514807, 5329817595487,33276057627697,207754954396765, 1297092388823683,8098236068810727] |