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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 29 |
| 4 | 192 |
| 5 | 1657 |
| 6 | 17980 |
| 7 | 237361 |
| 8 | 3726512 |
| 9 | 68389537 |
| 10 | 1445817556 |
| 11 | 34786395633 |
| 12 | 943051379976 |
| 13 | 28561453705681 |
| 14 | 959221358124188 |
| 15 | 35493038942592705 |
| 16 | 1438763782565929568 |
| 17 | 63572690326212167745 |
| 18 | 3048111097747838424484 |
| 19 | 157947658466567381928913 |
| 20 | 8813142621489336583785400 |
[1,2,6,29,192,1657,17980,237361,3726512,68389537, 1445817556,34786395633,943051379976, 28561453705681,959221358124188,35493038942592705, 1438763782565929568,63572690326212167745, 3048111097747838424484,157947658466567381928913, 8813142621489336583785400] |