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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 21 |
| 5 | 74 |
| 6 | 248 |
| 7 | 784 |
| 8 | 2355 |
| 9 | 6785 |
| 10 | 18897 |
| 11 | 51177 |
| 12 | 135358 |
| 13 | 350788 |
| 14 | 893038 |
| 15 | 2237998 |
| 16 | 5530485 |
| 17 | 13496371 |
| 18 | 32566359 |
| 19 | 77785039 |
| 20 | 184083080 |
| 21 | 432004206 |
| 22 | 1006097772 |
| 23 | 2326777196 |
| 24 | 5346673751 |
| 25 | 12213795349 |
| 26 | 27749494413 |
| 27 | 62729986469 |
| 28 | 141146690370 |
| 29 | 316216935240 |
| 30 | 705582559642 |
[1,1,2,6,21,74,248,784,2355,6785,18897,51177, 135358,350788,893038,2237998,5530485,13496371, 32566359,77785039,184083080,432004206,1006097772, 2326777196,5346673751,12213795349,27749494413, 62729986469,141146690370,316216935240, 705582559642] |