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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 14 |
| 4 | 85 |
| 5 | 640 |
| 6 | 5703 |
| 7 | 58760 |
| 8 | 685353 |
| 9 | 8925632 |
| 10 | 128231627 |
| 11 | 2014061568 |
| 12 | 34312150525 |
| 13 | 630043097216 |
| 14 | 12400033125647 |
| 15 | 260357810321664 |
| 16 | 5807790344591953 |
| 17 | 137144754146230272 |
| 18 | 3417248676737769619 |
| 19 | 89590823377278496768 |
| 20 | 2465026658283881339301 |
[1,1,3,14,85,640,5703,58760,685353,8925632, 128231627,2014061568,34312150525,630043097216, 12400033125647,260357810321664,5807790344591953, 137144754146230272,3417248676737769619, 89590823377278496768,2465026658283881339301] |