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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 12 |
| 4 | 48 |
| 5 | 188 |
| 6 | 790 |
| 7 | 3373 |
| 8 | 14775 |
| 9 | 65711 |
| 10 | 296183 |
| 11 | 1349263 |
| 12 | 6200429 |
| 13 | 28702895 |
| 14 | 133696901 |
| 15 | 626086696 |
| 16 | 2945367102 |
| 17 | 13911989913 |
| 18 | 65943630939 |
| 19 | 313555617506 |
| 20 | 1495083989143 |
| 21 | 7146639957156 |
| 22 | 34238554950923 |
| 23 | 164366582896944 |
| 24 | 790525990606840 |
| 25 | 3808495347158545 |
| 26 | 18376542286319936 |
| 27 | 88795969816237845 |
[1,1,4,12,48,188,790,3373,14775,65711,296183, 1349263,6200429,28702895,133696901,626086696, 2945367102,13911989913,65943630939,313555617506, 1495083989143,7146639957156,34238554950923, 164366582896944,790525990606840,3808495347158545, 18376542286319936,88795969816237845] |