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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 4 |
| 3 | 6 |
| 4 | 2 |
| 5 | 18 |
| 6 | 34 |
| 7 | 2 |
| 8 | 578 |
| 9 | 1154 |
| 10 | 2 |
| 11 | 665858 |
| 12 | 1331714 |
| 13 | 2 |
| 14 | 886731088898 |
| 15 | 1773462177794 |
| 16 | 2 |
| 17 | 1572584048032918633353218 |
| 18 | 3145168096065837266706434 |
| 19 | 2 |
| 20 | 4946041176255201878775086487573351061418968498178 |
| 21 | 9892082352510403757550172975146702122837936996354 |
[2,4,6,2,18,34,2,578,1154,2,665858,1331714,2, 886731088898,1773462177794,2, 1572584048032918633353218, 3145168096065837266706434,2, 4946041176255201878775086487573351061418968498178, 9892082352510403757550172975146702122837936996354] |