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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 1 |
| 6 | 3 |
| 7 | 2 |
| 8 | 5 |
| 9 | 4 |
| 10 | 9 |
| 11 | 7 |
| 12 | 23 |
| 13 | 18 |
| 14 | 74 |
| 15 | 106 |
| 16 | 619 |
| 17 | 2076 |
| 18 | 22526 |
| 19 | 112834 |
| 20 | 4799825 |
| 21 | 31138965 |
| 22 | 4207943011 |
| 23 | 115979718015 |
| 24 | 13482672647959 |
[0,0,1,1,2,1,3,2,5,4,9,7,23,18,74,106,619,2076, 22526,112834,4799825,31138965,4207943011, 115979718015,13482672647959] |