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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 2 |
| 6 | 5 |
| 7 | 12 |
| 8 | 30 |
| 9 | 75 |
| 10 | 194 |
| 11 | 501 |
| 12 | 1317 |
| 13 | 3485 |
| 14 | 9302 |
| 15 | 24976 |
| 16 | 67500 |
| 17 | 183290 |
| 18 | 500094 |
| 19 | 1369939 |
| 20 | 3766831 |
| 21 | 10391722 |
| 22 | 28756022 |
| 23 | 79794407 |
| 24 | 221987348 |
| 25 | 619019808 |
| 26 | 1729924110 |
| 27 | 4844242273 |
| 28 | 13590663071 |
| 29 | 38195831829 |
| 30 | 107523305566 |
| 31 | 303148601795 |
| 32 | 855922155734 |
| 33 | 2419923253795 |
[0,0,0,1,2,5,12,30,75,194,501,1317,3485,9302, 24976,67500,183290,500094,1369939,3766831, 10391722,28756022,79794407,221987348,619019808, 1729924110,4844242273,13590663071,38195831829, 107523305566,303148601795,855922155734, 2419923253795] |