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| n | a(n) |
|---|---|
| 3 | 0 |
| 4 | 0 |
| 5 | 2 |
| 6 | 8 |
| 7 | 6 |
| 8 | 16 |
| 9 | 58 |
| 10 | 120 |
| 11 | 254 |
| 12 | 668 |
| 13 | 1616 |
| 14 | 3750 |
| 15 | 9540 |
| 16 | 23832 |
| 17 | 59628 |
| 18 | 151807 |
| 19 | 392948 |
| 20 | 1014372 |
| 21 | 2648282 |
| 22 | 6968089 |
| 23 | 18372218 |
| 24 | 48650007 |
| 25 | 129494286 |
| 26 | 345288143 |
| 27 | 922430248 |
| 28 | 2471294134 |
| 29 | 6633522886 |
| 30 | 17828876698 |
| 31 | 47998957546 |
[0,0,2,8,6,16,58,120,254,668,1616,3750,9540,23832, 59628,151807,392948,1014372,2648282,6968089, 18372218,48650007,129494286,345288143,922430248, 2471294134,6633522886,17828876698,47998957546] |