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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 11 |
| 5 | 24 |
| 6 | 55 |
| 7 | 128 |
| 8 | 298 |
| 9 | 693 |
| 10 | 1611 |
| 11 | 3745 |
| 12 | 8706 |
| 13 | 20239 |
| 14 | 47050 |
| 15 | 109378 |
| 16 | 254273 |
| 17 | 591113 |
| 18 | 1374171 |
| 19 | 3194560 |
| 20 | 7426451 |
| 21 | 17264404 |
| 22 | 40134870 |
| 23 | 93302253 |
| 24 | 216901423 |
| 25 | 504234633 |
| 26 | 1172203306 |
| 27 | 2725042075 |
| 28 | 6334954246 |
| 29 | 14726981894 |
| 30 | 34236079265 |
[1,1,1,4,11,24,55,128,298,693,1611,3745,8706, 20239,47050,109378,254273,591113,1374171,3194560, 7426451,17264404,40134870,93302253,216901423, 504234633,1172203306,2725042075,6334954246, 14726981894,34236079265] |