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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 17 |
| 5 | 53 |
| 6 | 329 |
| 7 | 2805 |
| 8 | 46829 |
| 9 | 1364733 |
| 10 | 44089225 |
| 11 | 1990990191 |
| 12 | 141312602855 |
| 13 | 15682635595595 |
[1,1,1,17,53,329,2805,46829,1364733,44089225, 1990990191,141312602855,15682635595595] |