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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 25 |
| 6 | 108 |
| 7 | 492 |
| 8 | 2418 |
| 9 | 12240 |
| 10 | 64058 |
| 11 | 342192 |
| 12 | 1863319 |
| 13 | 10298447 |
| 14 | 57673979 |
| 15 | 326628929 |
| 16 | 1868216994 |
[1,1,2,7,25,108,492,2418,12240,64058,342192, 1863319,10298447,57673979,326628929,1868216994] |