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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 14 |
| 5 | 42 |
| 6 | 132 |
| 7 | 428 |
| 8 | 1421 |
| 9 | 4807 |
| 10 | 16510 |
| 11 | 57421 |
| 12 | 201824 |
| 13 | 715768 |
| 14 | 2558167 |
| 15 | 9204651 |
| 16 | 33315919 |
| 17 | 121218195 |
| 18 | 443107245 |
| 19 | 1626546453 |
| 20 | 5993256280 |
| 21 | 22158739970 |
| 22 | 82182744284 |
| 23 | 305670888560 |
| 24 | 1139892935454 |
| 25 | 4261095044346 |
| 26 | 15964169665031 |
| 27 | 59933390160322 |
[1,1,2,5,14,42,132,428,1421,4807,16510,57421, 201824,715768,2558167,9204651,33315919,121218195, 443107245,1626546453,5993256280,22158739970, 82182744284,305670888560,1139892935454, 4261095044346,15964169665031,59933390160322] |