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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 15 |
| 3 | 63 |
| 4 | 255 |
| 5 | 1019 |
| 6 | 4073 |
| 7 | 16289 |
| 8 | 65153 |
| 9 | 260609 |
| 10 | 1042417 |
| 11 | 4169595 |
| 12 | 16678079 |
| 13 | 66711107 |
| 14 | 266839591 |
| 15 | 1067339019 |
| 16 | 4269278705 |
| 17 | 17076805345 |
| 18 | 68305983505 |
| 19 | 273218982601 |
| 20 | 1092856125089 |
| 21 | 4371345280527 |
| 22 | 17485064248535 |
| 23 | 69938989522819 |
[3,15,63,255,1019,4073,16289,65153,260609,1042417, 4169595,16678079,66711107,266839591,1067339019, 4269278705,17076805345,68305983505,273218982601, 1092856125089,4371345280527,17485064248535, 69938989522819] |