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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 4 |
| 3 | 17 |
| 4 | 130 |
| 5 | 1283 |
| 6 | 6889 |
| 7 | 40037 |
| 8 | 638521 |
| 9 | 10126943 |
| 10 | 186814849 |
| 11 | 2092495862 |
[2,4,17,130,1283,6889,40037,638521,10126943, 186814849,2092495862] |