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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 15 |
| 4 | 63 |
| 5 | 217 |
| 6 | 987 |
| 7 | 3739 |
| 8 | 17041 |
| 9 | 67427 |
| 10 | 312401 |
| 11 | 1278837 |
| 12 | 5957503 |
| 13 | 24909735 |
| 14 | 116754341 |
| 15 | 496697033 |
| 16 | 2336947601 |
| 17 | 10068508359 |
| 18 | 47525309535 |
| 19 | 206915190169 |
| 20 | 979136680151 |
| 21 | 4298958028443 |
| 22 | 20384884952523 |
| 23 | 90137007956037 |
| 24 | 428149816291391 |
| 25 | 1904522963616211 |
| 26 | 9059540607832431 |
| 27 | 40506805212447825 |
[1,1,5,15,63,217,987,3739,17041,67427,312401, 1278837,5957503,24909735,116754341,496697033, 2336947601,10068508359,47525309535,206915190169, 979136680151,4298958028443,20384884952523, 90137007956037,428149816291391,1904522963616211, 9059540607832431,40506805212447825] |