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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 19 |
| 4 | 121 |
| 5 | 1161 |
| 6 | 9931 |
| 7 | 124363 |
| 8 | 1542129 |
| 9 | 21594961 |
| 10 | 335083411 |
| 11 | 5712781251 |
| 12 | 104044684393 |
| 13 | 2036445474649 |
| 14 | 42781075481691 |
| 15 | 943820382272251 |
| 16 | 22433542236603361 |
| 17 | 556276331238284193 |
| 18 | 14612462927067954979 |
| 19 | 401110580118493111411 |
| 20 | 11553483337639043003481 |
[1,1,3,19,121,1161,9931,124363,1542129,21594961, 335083411,5712781251,104044684393,2036445474649, 42781075481691,943820382272251,22433542236603361, 556276331238284193,14612462927067954979, 401110580118493111411,11553483337639043003481] |