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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 6 |
| 3 | 52 |
| 4 | 588 |
| 5 | 8174 |
| 6 | 134537 |
| 7 | 2554647 |
| 8 | 54909468 |
| 9 | 1316675221 |
| 10 | 34820961457 |
| 11 | 1006230148609 |
| 12 | 31529224324159 |
| 13 | 1064355502971193 |
| 14 | 38497326001639439 |
| 15 | 1484865225798412485 |
| 16 | 60822449267067095601 |
| 17 | 2636248249383130776940 |
| 18 | 120520100503562054999860 |
| 19 | 5794815395039941996204424 |
[1,1,6,52,588,8174,134537,2554647,54909468, 1316675221,34820961457,1006230148609, 31529224324159,1064355502971193,38497326001639439, 1484865225798412485,60822449267067095601, 2636248249383130776940,120520100503562054999860, 5794815395039941996204424] |