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| n | a(n) |
|---|---|
| 1 | -1 |
| 2 | 2 |
| 3 | 9 |
| 4 | 13 |
| 5 | 31 |
| 6 | 57 |
| 7 | 119 |
| 8 | 233 |
| 9 | 471 |
| 10 | 937 |
| 11 | 1879 |
| 12 | 3753 |
| 13 | 7511 |
| 14 | 15017 |
| 15 | 30039 |
| 16 | 60073 |
| 17 | 120151 |
| 18 | 240297 |
| 19 | 480599 |
| 20 | 961193 |
| 21 | 1922391 |
| 22 | 3844777 |
| 23 | 7689559 |
| 24 | 15379113 |
| 25 | 30758231 |
| 26 | 61516457 |
| 27 | 123032919 |
| 28 | 246065833 |
| 29 | 492131671 |
| 30 | 984263337 |
| 31 | 1968526679 |
| 32 | 3937053353 |
| 33 | 7874106711 |
[-1,2,9,13,31,57,119,233,471,937,1879,3753,7511, 15017,30039,60073,120151,240297,480599,961193, 1922391,3844777,7689559,15379113,30758231, 61516457,123032919,246065833,492131671,984263337, 1968526679,3937053353,7874106711] |