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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 2 |
| 5 | 5 |
| 6 | 5 |
| 7 | 15 |
| 8 | 15 |
| 9 | 52 |
| 10 | 52 |
| 11 | 203 |
| 12 | 203 |
| 13 | 877 |
| 14 | 877 |
| 15 | 4140 |
| 16 | 4140 |
| 17 | 21147 |
| 18 | 21147 |
| 19 | 115975 |
| 20 | 115975 |
| 21 | 678570 |
| 22 | 678570 |
| 23 | 4213597 |
| 24 | 4213597 |
| 25 | 27644437 |
| 26 | 27644437 |
| 27 | 190899322 |
| 28 | 190899322 |
| 29 | 1382958545 |
| 30 | 1382958545 |
[1,1,1,2,2,5,5,15,15,52,52,203,203,877,877,4140, 4140,21147,21147,115975,115975,678570,678570, 4213597,4213597,27644437,27644437,190899322, 190899322,1382958545,1382958545] |