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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 10 |
| 6 | 31 |
| 7 | 120 |
| 8 | 578 |
| 9 | 3422 |
| 10 | 24504 |
| 11 | 208833 |
| 12 | 2086777 |
| 13 | 24123293 |
| 14 | 318800755 |
| 15 | 4766262421 |
| 16 | 79874304340 |
| 17 | 1488227986802 |
[1,1,2,4,10,31,120,578,3422,24504,208833,2086777, 24123293,318800755,4766262421,79874304340, 1488227986802] |