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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 101 |
| 5 | 931 |
| 6 | 12391 |
| 7 | 178809 |
| 8 | 3331721 |
| 9 | 66288142 |
| 10 | 1589753211 |
| 11 | 40104031166 |
| 12 | 1183380156013 |
| 13 | 36187564837217 |
| 14 | 1262524447510383 |
| 15 | 45533370885563716 |
| 16 | 1834219414937219601 |
| 17 | 76016894083755947753 |
| 18 | 3479900167920331954531 |
| 19 | 162982921698852088968886 |
| 20 | 8341707623665223127224821 |
[1,1,3,13,101,931,12391,178809,3331721,66288142, 1589753211,40104031166,1183380156013, 36187564837217,1262524447510383,45533370885563716, 1834219414937219601,76016894083755947753, 3479900167920331954531,162982921698852088968886, 8341707623665223127224821] |