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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 10 |
| 5 | 22 |
| 6 | 46 |
| 7 | 106 |
| 8 | 406 |
| 9 | 826 |
| 10 | 2386 |
| 11 | 5950 |
| 12 | 12466 |
| 13 | 37990 |
| 14 | 141262 |
| 15 | 577486 |
[1,2,4,10,22,46,106,406,826,2386,5950,12466,37990, 141262,577486] |