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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 20 |
| 4 | 49 |
| 5 | 210 |
| 6 | 429 |
| 7 | 2860 |
| 8 | 7293 |
| 9 | 34034 |
| 10 | 113373 |
| 11 | 537472 |
| 12 | 1359507 |
| 13 | 6611810 |
| 14 | 24627135 |
| 15 | 37917616 |
| 16 | 177181213 |
| 17 | 973514514 |
| 18 | 1647439975 |
| 19 | 12026570280 |
| 20 | 17818756259 |
| 21 | 98555142278 |
| 22 | 502860886675 |
| 23 | 4577646742140 |
| 24 | 6402665244089 |
[1,2,5,20,49,210,429,2860,7293,34034,113373, 537472,1359507,6611810,24627135,37917616, 177181213,973514514,1647439975,12026570280, 17818756259,98555142278,502860886675, 4577646742140,6402665244089] |