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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | 1 |
| 7 | 1 |
| 8 | 2 |
| 9 | 4 |
| 10 | 8 |
| 11 | 16 |
| 12 | 34 |
| 13 | 72 |
| 14 | 158 |
| 15 | 348 |
| 16 | 784 |
| 17 | 1777 |
| 18 | 4080 |
| 19 | 9425 |
| 20 | 21965 |
| 21 | 51456 |
| 22 | 121300 |
| 23 | 287215 |
| 24 | 683268 |
| 25 | 1631532 |
| 26 | 3910235 |
| 27 | 9401000 |
| 28 | 22670058 |
| 29 | 54813780 |
| 30 | 132867903 |
[0,0,0,0,1,1,1,2,4,8,16,34,72,158,348,784,1777, 4080,9425,21965,51456,121300,287215,683268, 1631532,3910235,9401000,22670058,54813780, 132867903] |