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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 1 |
| 6 | 5 |
| 7 | 17 |
| 8 | 41 |
| 9 | 145 |
| 10 | 657 |
| 11 | 4553 |
| 12 | 32425 |
| 13 | 257569 |
| 14 | 2670753 |
| 15 | 36201945 |
| 16 | 564616361 |
| 17 | 10290347089 |
| 18 | 235475912465 |
| 19 | 6833463711081 |
| 20 | 238928359316057 |
| 21 | 9863518167137825 |
[1,1,1,1,1,5,17,41,145,657,4553,32425,257569, 2670753,36201945,564616361,10290347089, 235475912465,6833463711081,238928359316057, 9863518167137825] |