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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 15 |
| 3 | 55 |
| 4 | 216 |
| 5 | 729 |
| 6 | 2621 |
| 7 | 8535 |
| 8 | 28689 |
| 9 | 91749 |
| 10 | 296538 |
| 11 | 929712 |
| 12 | 2939063 |
| 13 | 9093255 |
| 14 | 28257123 |
| 15 | 86681608 |
| 16 | 266368959 |
| 17 | 811501848 |
| 18 | 2475331535 |
| 19 | 7505567037 |
| 20 | 22772955015 |
| 21 | 68828023329 |
| 22 | 208079886258 |
| 23 | 627418618533 |
| 24 | 1892181244828 |
| 25 | 5696253823476 |
| 26 | 17149663331259 |
[1,3,15,55,216,729,2621,8535,28689,91749,296538, 929712,2939063,9093255,28257123,86681608, 266368959,811501848,2475331535,7505567037, 22772955015,68828023329,208079886258,627418618533, 1892181244828,5696253823476,17149663331259] |