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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 31 |
| 5 | 111 |
| 6 | 415 |
| 7 | 1591 |
| 8 | 6229 |
| 9 | 24773 |
| 10 | 99795 |
| 11 | 406225 |
| 12 | 1668071 |
| 13 | 6900295 |
| 14 | 28725759 |
| 15 | 120243143 |
| 16 | 505751889 |
| 17 | 2136282633 |
| 18 | 9057752963 |
| 19 | 38534668209 |
| 20 | 164439768551 |
| 21 | 703658271103 |
| 22 | 3018625303199 |
| 23 | 12979441615631 |
| 24 | 55926921211749 |
[1,1,3,9,31,111,415,1591,6229,24773,99795,406225, 1668071,6900295,28725759,120243143,505751889, 2136282633,9057752963,38534668209,164439768551, 703658271103,3018625303199,12979441615631, 55926921211749] |