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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 11 |
| 4 | 34 |
| 5 | 123 |
| 6 | 419 |
| 7 | 1501 |
| 8 | 5732 |
| 9 | 20925 |
| 10 | 80815 |
| 11 | 314395 |
| 12 | 1209220 |
| 13 | 4820559 |
| 14 | 19083662 |
| 15 | 75911851 |
| 16 | 307724890 |
| 17 | 1237790403 |
| 18 | 5033871995 |
| 19 | 20612532057 |
| 20 | 84134008596 |
| 21 | 346989672093 |
| 22 | 1432118446248 |
| 23 | 5918323829069 |
| 24 | 24628670168512 |
| 25 | 102394999382253 |
| 26 | 427288651678265 |
| 27 | 1789242768786287 |
| 28 | 7490596712558988 |
[1,1,4,11,34,123,419,1501,5732,20925,80815,314395, 1209220,4820559,19083662,75911851,307724890, 1237790403,5033871995,20612532057,84134008596, 346989672093,1432118446248,5918323829069, 24628670168512,102394999382253,427288651678265, 1789242768786287,7490596712558988] |