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| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 13 |
| 2 | 89 |
| 3 | 637 |
| 4 | 4721 |
| 5 | 35893 |
| 6 | 277769 |
| 7 | 2175277 |
| 8 | 17167841 |
| 9 | 136170853 |
| 10 | 1083507449 |
| 11 | 8638762717 |
| 12 | 68963617361 |
| 13 | 550976517013 |
| 14 | 4404150026729 |
| 15 | 35214889666957 |
| 16 | 281627564601281 |
| 17 | 2252562753138373 |
| 18 | 18018213206747609 |
| 19 | 144134261562183997 |
[2,13,89,637,4721,35893,277769,2175277,17167841, 136170853,1083507449,8638762717,68963617361, 550976517013,4404150026729,35214889666957, 281627564601281,2252562753138373, 18018213206747609,144134261562183997] |