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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 15 |
| 4 | 65 |
| 5 | 231 |
| 6 | 1077 |
| 7 | 4077 |
| 8 | 19521 |
| 9 | 77847 |
| 10 | 375523 |
| 11 | 1542669 |
| 12 | 7503275 |
| 13 | 31482945 |
| 14 | 153831367 |
| 15 | 656080547 |
| 16 | 3217363353 |
| 17 | 13890626113 |
| 18 | 68303798347 |
| 19 | 297856509483 |
| 20 | 1467615828795 |
| 21 | 6451956824907 |
| 22 | 31844333302963 |
| 23 | 140944569490221 |
| 24 | 696579282949195 |
| 25 | 3100862322964479 |
| 26 | 15342444196387139 |
| 27 | 68634610543557457 |
[1,1,5,15,65,231,1077,4077,19521,77847,375523, 1542669,7503275,31482945,153831367,656080547, 3217363353,13890626113,68303798347,297856509483, 1467615828795,6451956824907,31844333302963, 140944569490221,696579282949195,3100862322964479, 15342444196387139,68634610543557457] |