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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 1 |
| 6 | 5 |
| 7 | 17 |
| 8 | 41 |
| 9 | 159 |
| 10 | 789 |
| 11 | 4693 |
| 12 | 37959 |
| 13 | 362149 |
| 14 | 3798435 |
| 15 | 51198703 |
| 16 | 878343647 |
| 17 | 18110228679 |
| 18 | 463058495339 |
| 19 | 14563433819389 |
| 20 | 553118211838649 |
| 21 | 25843199757659397 |
[1,1,1,1,1,5,17,41,159,789,4693,37959,362149, 3798435,51198703,878343647,18110228679, 463058495339,14563433819389,553118211838649, 25843199757659397] |