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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 7 |
| 5 | 25 |
| 6 | 89 |
| 7 | 559 |
| 8 | 4332 |
| 9 | 47525 |
| 10 | 720844 |
| 11 | 13515353 |
| 12 | 345530332 |
| 13 | 11945906159 |
| 14 | 546900316419 |
| 15 | 33704239869671 |
| 16 | 2765958377374818 |
[1,1,1,7,25,89,559,4332,47525,720844,13515353, 345530332,11945906159,546900316419,33704239869671, 2765958377374818] |