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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 0 |
| 8 | 1 |
| 9 | 4 |
| 10 | 15 |
| 11 | 14 |
| 12 | 52 |
| 13 | 83 |
| 14 | 199 |
| 15 | 260 |
| 16 | 850 |
| 17 | 1204 |
| 18 | 3435 |
| 19 | 4596 |
| 20 | 13102 |
| 21 | 19095 |
| 22 | 51386 |
| 23 | 72485 |
| 24 | 199933 |
| 25 | 296317 |
| 26 | 777795 |
| 27 | 1152625 |
| 28 | 3017298 |
| 29 | 4571188 |
| 30 | 11663138 |
| 31 | 17768490 |
| 32 | 45124684 |
| 33 | 70038513 |
[0,0,0,0,0,0,0,1,4,15,14,52,83,199,260,850,1204, 3435,4596,13102,19095,51386,72485,199933,296317, 777795,1152625,3017298,4571188,11663138,17768490, 45124684,70038513] |