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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 19 |
| 5 | 97 |
| 6 | 863 |
| 7 | 18767 |
| 8 | 490889 |
| 9 | 19713443 |
| 10 | 1413873475 |
| 11 | 167866752937 |
| 12 | 30662833126025 |
| 13 | 9066289386941209 |
[1,1,5,19,97,863,18767,490889,19713443,1413873475, 167866752937,30662833126025,9066289386941209] |