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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 15 |
| 4 | 67 |
| 5 | 215 |
| 6 | 1043 |
| 7 | 3861 |
| 8 | 18385 |
| 9 | 69261 |
| 10 | 338609 |
| 11 | 1353969 |
| 12 | 6559381 |
| 13 | 26398681 |
| 14 | 129688109 |
| 15 | 539731863 |
| 16 | 2636124491 |
| 17 | 11003741583 |
| 18 | 54223215931 |
| 19 | 231338016843 |
| 20 | 1135230145991 |
| 21 | 4850631360147 |
| 22 | 23952841458207 |
| 23 | 103949123901271 |
| 24 | 511679547285827 |
| 25 | 2222260035489935 |
| 26 | 10990667620450459 |
| 27 | 48295910120993503 |
[1,1,5,15,67,215,1043,3861,18385,69261,338609, 1353969,6559381,26398681,129688109,539731863, 2636124491,11003741583,54223215931,231338016843, 1135230145991,4850631360147,23952841458207, 103949123901271,511679547285827,2222260035489935, 10990667620450459,48295910120993503] |