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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 1 |
| 7 | 6 |
| 8 | 21 |
| 9 | 42 |
| 10 | 112 |
| 11 | 252 |
| 12 | 378 |
| 13 | 759 |
| 14 | 1419 |
| 15 | 1914 |
| 16 | 3564 |
| 17 | 6864 |
| 18 | 9295 |
| 19 | 20020 |
| 20 | 45055 |
| 21 | 63083 |
| 22 | 146648 |
| 23 | 331568 |
| 24 | 456484 |
| 25 | 1007454 |
| 26 | 2156994 |
| 27 | 2896664 |
| 28 | 6165494 |
| 29 | 13079094 |
| 30 | 17441739 |
| 31 | 37871064 |
| 32 | 82898739 |
| 33 | 111029050 |
| 34 | 247813500 |
[0,0,0,0,0,1,6,21,42,112,252,378,759,1419,1914, 3564,6864,9295,20020,45055,63083,146648,331568, 456484,1007454,2156994,2896664,6165494,13079094, 17441739,37871064,82898739,111029050,247813500] |