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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 35 |
| 6 | 129 |
| 7 | 495 |
| 8 | 2101 |
| 9 | 9154 |
| 10 | 41356 |
| 11 | 189466 |
| 12 | 880156 |
| 13 | 4120515 |
| 14 | 19425037 |
[1,1,2,4,12,35,129,495,2101,9154,41356,189466, 880156,4120515,19425037] |