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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 3 |
| 6 | 9 |
| 7 | 23 |
| 8 | 65 |
| 9 | 186 |
| 10 | 507 |
| 11 | 1380 |
| 12 | 3764 |
| 13 | 10270 |
| 14 | 28001 |
| 15 | 76568 |
| 16 | 209749 |
| 17 | 575900 |
| 18 | 1584769 |
| 19 | 4371279 |
| 20 | 12083764 |
| 21 | 33477190 |
| 22 | 92939305 |
| 23 | 258537475 |
| 24 | 720575302 |
| 25 | 2012021934 |
| 26 | 5627886815 |
| 27 | 15768237664 |
| 28 | 44249863373 |
| 29 | 124365487416 |
| 30 | 350038837208 |
| 31 | 986579529425 |
[0,0,0,0,0,3,9,23,65,186,507,1380,3764,10270, 28001,76568,209749,575900,1584769,4371279, 12083764,33477190,92939305,258537475,720575302, 2012021934,5627886815,15768237664,44249863373, 124365487416,350038837208,986579529425] |