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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | 1 |
| 7 | 0 |
| 8 | 0 |
| 9 | 2 |
| 10 | 0 |
| 11 | 0 |
| 12 | 3 |
| 13 | 11 |
| 14 | 2 |
| 15 | 13 |
| 16 | 21 |
| 17 | 26 |
| 18 | 49 |
| 19 | 91 |
| 20 | 186 |
| 21 | 108 |
| 22 | 335 |
| 23 | 937 |
| 24 | 500 |
| 25 | 1681 |
| 26 | 4208 |
| 27 | 4156 |
[1,0,0,0,1,1,0,0,2,0,0,3,11,2,13,21,26,49,91,186, 108,335,937,500,1681,4208,4156] |