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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 3 |
| 6 | 7 |
| 7 | 19 |
| 8 | 43 |
| 9 | 173 |
| 10 | 1027 |
| 11 | 6241 |
| 12 | 39873 |
| 13 | 317065 |
| 14 | 3440337 |
| 15 | 46130903 |
| 16 | 694355761 |
| 17 | 12449375951 |
| 18 | 281232131103 |
| 19 | 7909400224367 |
| 20 | 265990951612641 |
[1,1,1,1,3,7,19,43,173,1027,6241,39873,317065, 3440337,46130903,694355761,12449375951, 281232131103,7909400224367,265990951612641] |