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| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 13 |
| 2 | 71 |
| 3 | 376 |
| 4 | 1991 |
| 5 | 10564 |
| 6 | 56051 |
| 7 | 297384 |
| 8 | 1577797 |
| 9 | 8371133 |
| 10 | 44413759 |
| 11 | 235640987 |
| 12 | 1250213362 |
| 13 | 6633113651 |
| 14 | 35192550325 |
| 15 | 186717077925 |
| 16 | 990643385291 |
| 17 | 5255942989944 |
| 18 | 27885853904294 |
| 19 | 147950776760552 |
| 20 | 784965467407868 |
| 21 | 4164701250741605 |
| 22 | 22096177765889378 |
[2,13,71,376,1991,10564,56051,297384,1577797, 8371133,44413759,235640987,1250213362,6633113651, 35192550325,186717077925,990643385291, 5255942989944,27885853904294,147950776760552, 784965467407868,4164701250741605, 22096177765889378] |