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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 1 |
| 7 | 2 |
| 8 | 6 |
| 9 | 22 |
| 10 | 86 |
| 11 | 342 |
| 12 | 1366 |
| 13 | 5462 |
| 14 | 21591 |
| 15 | 85600 |
| 16 | 339616 |
| 17 | 1347632 |
| 18 | 5347632 |
| 19 | 21219888 |
| 20 | 84199984 |
| 21 | 334092848 |
| 22 | 1325649969 |
| 23 | 5260075594 |
| 24 | 20871578510 |
| 25 | 82816815054 |
| 26 | 328610657230 |
| 27 | 1303901211854 |
| 28 | 5173777051854 |
| 29 | 20529140314318 |
[0,0,0,0,0,0,1,2,6,22,86,342,1366,5462,21591, 85600,339616,1347632,5347632,21219888,84199984, 334092848,1325649969,5260075594,20871578510, 82816815054,328610657230,1303901211854, 5173777051854,20529140314318] |