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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 13 |
| 3 | 71 |
| 4 | 457 |
| 5 | 3355 |
| 6 | 27509 |
| 7 | 248127 |
| 8 | 2434129 |
| 9 | 25741939 |
| 10 | 291397789 |
| 11 | 3510328695 |
| 12 | 44782460313 |
| 13 | 602513988107 |
| 14 | 8518757813637 |
| 15 | 126179029108463 |
| 16 | 1952609274344353 |
| 17 | 31492811964616163 |
| 18 | 528249539951292461 |
| 19 | 9197240228562763687 |
| 20 | 165923214676585626729 |
[1,3,13,71,457,3355,27509,248127,2434129,25741939, 291397789,3510328695,44782460313,602513988107, 8518757813637,126179029108463,1952609274344353, 31492811964616163,528249539951292461, 9197240228562763687,165923214676585626729] |