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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 4 |
| 4 | 15 |
| 5 | 56 |
| 6 | 84 |
| 7 | 330 |
| 8 | 495 |
| 9 | 2002 |
| 10 | 8008 |
| 11 | 12376 |
| 12 | 50388 |
| 13 | 203490 |
| 14 | 319770 |
| 15 | 1307504 |
| 16 | 2042975 |
| 17 | 8436285 |
| 18 | 34597290 |
| 19 | 54627300 |
| 20 | 225792840 |
| 21 | 354817320 |
| 22 | 1476337800 |
| 23 | 6107086800 |
| 24 | 9669554100 |
| 25 | 40225345056 |
| 26 | 166509721602 |
| 27 | 265182149218 |
[1,1,3,4,15,56,84,330,495,2002,8008,12376,50388, 203490,319770,1307504,2042975,8436285,34597290, 54627300,225792840,354817320,1476337800, 6107086800,9669554100,40225345056,166509721602, 265182149218] |