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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 9 |
| 4 | 25 |
| 5 | 61 |
| 6 | 197 |
| 7 | 597 |
| 8 | 2165 |
| 9 | 7861 |
| 10 | 30549 |
| 11 | 118869 |
| 12 | 471765 |
| 13 | 1873621 |
| 14 | 7479637 |
| 15 | 29864277 |
| 16 | 119397205 |
[1,2,4,9,25,61,197,597,2165,7861,30549,118869, 471765,1873621,7479637,29864277,119397205] |