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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 4 |
| 3 | 8 |
| 4 | 17 |
| 5 | 36 |
| 6 | 85 |
| 7 | 216 |
| 8 | 640 |
| 9 | 2292 |
| 10 | 9665 |
| 11 | 80836 |
| 12 | 1070709 |
| 13 | 27652010 |
| 14 | 1345914266 |
| 15 | 115596164732 |
[2,4,8,17,36,85,216,640,2292,9665,80836,1070709, 27652010,1345914266,115596164732] |