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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 19 |
| 5 | 70 |
| 6 | 264 |
| 7 | 1038 |
| 8 | 4155 |
| 9 | 16896 |
| 10 | 69584 |
| 11 | 289146 |
| 12 | 1211873 |
| 13 | 5111178 |
| 14 | 21686612 |
| 15 | 92453594 |
| 16 | 395888507 |
| 17 | 1701506820 |
| 18 | 7337867736 |
| 19 | 31739124866 |
| 20 | 137656095241 |
| 21 | 598476364166 |
| 22 | 2607710997676 |
| 23 | 11385288787534 |
| 24 | 49800060551081 |
[1,2,6,19,70,264,1038,4155,16896,69584,289146, 1211873,5111178,21686612,92453594,395888507, 1701506820,7337867736,31739124866,137656095241, 598476364166,2607710997676,11385288787534, 49800060551081] |