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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 8 |
| 4 | 24 |
| 5 | 73 |
| 6 | 219 |
| 7 | 656 |
| 8 | 1968 |
| 9 | 5905 |
| 10 | 17715 |
| 11 | 53144 |
| 12 | 159432 |
| 13 | 478297 |
| 14 | 1434891 |
| 15 | 4304672 |
| 16 | 12914016 |
| 17 | 38742049 |
| 18 | 116226147 |
| 19 | 348678440 |
| 20 | 1046035320 |
| 21 | 3138105961 |
| 22 | 9414317883 |
| 23 | 28242953648 |
| 24 | 84728860944 |
| 25 | 254186582833 |
[0,1,3,8,24,73,219,656,1968,5905,17715,53144, 159432,478297,1434891,4304672,12914016,38742049, 116226147,348678440,1046035320,3138105961, 9414317883,28242953648,84728860944,254186582833] |