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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 42 |
| 4 | 497 |
| 5 | 7620 |
| 6 | 143979 |
| 7 | 3241406 |
| 8 | 84847489 |
| 9 | 2534788296 |
| 10 | 85170416115 |
| 11 | 3180919433802 |
| 12 | 130771002469953 |
| 13 | 5869920100483452 |
| 14 | 285705285804636411 |
| 15 | 14989889385040915830 |
| 16 | 843420165009747027969 |
| 17 | 50664760467069168337680 |
| 18 | 3236433107379299238343779 |
[1,1,5,42,497,7620,143979,3241406,84847489, 2534788296,85170416115,3180919433802, 130771002469953,5869920100483452, 285705285804636411,14989889385040915830, 843420165009747027969,50664760467069168337680, 3236433107379299238343779] |