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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 3 |
| 6 | 8 |
| 7 | 14 |
| 8 | 39 |
| 9 | 96 |
| 10 | 297 |
| 11 | 915 |
| 12 | 3308 |
| 13 | 12417 |
| 14 | 51347 |
| 15 | 222595 |
| 16 | 1016975 |
| 17 | 4799520 |
| 18 | 23301779 |
| 19 | 115405815 |
| 20 | 581071711 |
| 21 | 2963793396 |
| 22 | 15283327150 |
| 23 | 79544488072 |
| 24 | 417377448058 |
[0,1,1,2,3,8,14,39,96,297,915,3308,12417,51347, 222595,1016975,4799520,23301779,115405815, 581071711,2963793396,15283327150,79544488072, 417377448058] |