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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 6 |
| 4 | 16 |
| 5 | 35 |
| 6 | 78 |
| 7 | 168 |
| 8 | 352 |
| 9 | 735 |
| 10 | 1535 |
| 11 | 3201 |
| 12 | 6670 |
| 13 | 13897 |
| 14 | 28952 |
| 15 | 60311 |
| 16 | 125632 |
| 17 | 261698 |
| 18 | 545127 |
| 19 | 1135516 |
| 20 | 2365311 |
| 21 | 4927005 |
| 22 | 10263077 |
| 23 | 21378247 |
| 24 | 44531422 |
| 25 | 92760060 |
| 26 | 193221509 |
| 27 | 402485199 |
| 28 | 838386656 |
[0,0,6,16,35,78,168,352,735,1535,3201,6670,13897, 28952,60311,125632,261698,545127,1135516,2365311, 4927005,10263077,21378247,44531422,92760060, 193221509,402485199,838386656] |