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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 61 |
| 5 | 441 |
| 6 | 3031 |
| 7 | 28813 |
| 8 | 267513 |
| 9 | 3088081 |
| 10 | 36278731 |
| 11 | 491262861 |
| 12 | 6962025973 |
| 13 | 108395586313 |
| 14 | 1791145742751 |
| 15 | 31601369155021 |
| 16 | 594291393830641 |
| 17 | 11740929829286433 |
| 18 | 246910933786777363 |
| 19 | 5406641472165854221 |
| 20 | 125497950720670828461 |
| 21 | 3018786042678264770521 |
[1,1,3,13,61,441,3031,28813,267513,3088081, 36278731,491262861,6962025973,108395586313, 1791145742751,31601369155021,594291393830641, 11740929829286433,246910933786777363, 5406641472165854221,125497950720670828461, 3018786042678264770521] |