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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 4 |
| 3 | 8 |
| 4 | 22 |
| 5 | 98 |
| 6 | 388 |
| 7 | 16648 |
| 8 | 132358 |
| 9 | 1311234 |
| 10 | 1073743876 |
| 11 | 17179877384 |
| 12 | 274877943814 |
| 13 | 4398113693698 |
| 14 | 72083983122432004 |
| 15 | 3458834890081107976 |
| 16 | 110681871838615896070 |
| 17 | 38686511673635471463677954 |
| 18 | 2475908412805686633409019908 |
| 19 | 198070557401964757114570145800 |
[2,4,8,22,98,388,16648,132358,1311234,1073743876, 17179877384,274877943814,4398113693698, 72083983122432004,3458834890081107976, 110681871838615896070,38686511673635471463677954, 2475908412805686633409019908, 198070557401964757114570145800] |