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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 4 |
| 3 | 6 |
| 4 | 8 |
| 5 | 22 |
| 6 | 51 |
| 7 | 118 |
| 8 | 313 |
| 9 | 796 |
| 10 | 2022 |
| 11 | 5460 |
| 12 | 14756 |
| 13 | 41508 |
| 14 | 116504 |
| 15 | 331022 |
| 16 | 944930 |
| 17 | 2716758 |
| 18 | 7851206 |
[2,4,6,8,22,51,118,313,796,2022,5460,14756,41508, 116504,331022,944930,2716758,7851206] |