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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 7 |
| 3 | 15 |
| 4 | 59 |
| 5 | 143 |
| 6 | 367 |
| 7 | 1039 |
| 8 | 2755 |
| 9 | 7395 |
| 10 | 20007 |
| 11 | 53727 |
| 12 | 144635 |
| 13 | 389535 |
| 14 | 1048159 |
| 15 | 2821535 |
| 16 | 7595267 |
| 17 | 20443523 |
| 18 | 55029319 |
| 19 | 148125295 |
| 20 | 398712379 |
| 21 | 1073232175 |
| 22 | 2888862159 |
| 23 | 7776059055 |
| 24 | 20931132355 |
| 25 | 56341155043 |
| 26 | 151655701607 |
| 27 | 408217663167 |
| 28 | 1098815603707 |
| 29 | 2957725352255 |
[3,7,15,59,143,367,1039,2755,7395,20007,53727, 144635,389535,1048159,2821535,7595267,20443523, 55029319,148125295,398712379,1073232175, 2888862159,7776059055,20931132355,56341155043, 151655701607,408217663167,1098815603707, 2957725352255] |