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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | 1 |
| 7 | 3 |
| 8 | 9 |
| 9 | 29 |
| 10 | 99 |
| 11 | 356 |
| 12 | 1343 |
| 13 | 5279 |
| 14 | 21584 |
| 15 | 91324 |
| 16 | 399456 |
| 17 | 1799568 |
| 18 | 8343404 |
| 19 | 39702144 |
| 20 | 193768604 |
| 21 | 967992476 |
| 22 | 4946617328 |
| 23 | 25817913584 |
| 24 | 137549830384 |
| 25 | 747137750064 |
| 26 | 4135349698416 |
| 27 | 23301072909248 |
| 28 | 133591802704944 |
| 29 | 778722128953904 |
| 30 | 4613070010373504 |
[0,0,0,0,0,1,1,3,9,29,99,356,1343,5279,21584, 91324,399456,1799568,8343404,39702144,193768604, 967992476,4946617328,25817913584,137549830384, 747137750064,4135349698416,23301072909248, 133591802704944,778722128953904,4613070010373504] |