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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 15 |
| 5 | 102 |
| 6 | 861 |
| 7 | 8593 |
| 8 | 98453 |
| 9 | 1269924 |
| 10 | 18187062 |
| 11 | 286183564 |
| 12 | 4907331899 |
| 13 | 91082993194 |
| 14 | 1819518069135 |
| 15 | 38929958186607 |
| 16 | 888318740697313 |
| 17 | 21536467340324252 |
| 18 | 552893064959418966 |
| 19 | 14985039828839650746 |
[1,1,1,3,15,102,861,8593,98453,1269924,18187062, 286183564,4907331899,91082993194,1819518069135, 38929958186607,888318740697313,21536467340324252, 552893064959418966,14985039828839650746] |