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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 3 |
| 6 | 5 |
| 7 | 9 |
| 8 | 19 |
| 9 | 56 |
| 10 | 167 |
| 11 | 758 |
| 12 | 2457 |
| 13 | 14728 |
| 14 | 66625 |
| 15 | 526225 |
| 16 | 3298653 |
| 17 | 34425031 |
| 18 | 276512141 |
| 19 | 3848586911 |
| 20 | 41626261490 |
[1,1,1,1,3,5,9,19,56,167,758,2457,14728,66625, 526225,3298653,34425031,276512141,3848586911, 41626261490] |