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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 15 |
| 5 | 50 |
| 6 | 180 |
| 7 | 690 |
| 8 | 2792 |
| 9 | 11857 |
| 10 | 52633 |
| 11 | 243455 |
| 12 | 1170525 |
| 13 | 5837934 |
| 14 | 30151474 |
| 15 | 161021581 |
| 16 | 888001485 |
| 17 | 5051014786 |
| 18 | 29600662480 |
| 19 | 178541105770 |
| 20 | 1107321666920 |
| 21 | 7055339825171 |
| 22 | 46142654894331 |
| 23 | 309513540865544 |
| 24 | 2127744119042216 |
| 25 | 14979904453920111 |
| 26 | 107932371558460341 |
| 27 | 795363217306369817 |
| 28 | 5990768203554158167 |
| 29 | 46094392105916344968 |
| 30 | 362092868720288824992 |
[1,1,2,5,15,50,180,690,2792,11857,52633,243455, 1170525,5837934,30151474,161021581,888001485, 5051014786,29600662480,178541105770,1107321666920, 7055339825171,46142654894331,309513540865544, 2127744119042216,14979904453920111, 107932371558460341,795363217306369817, 5990768203554158167,46094392105916344968, 362092868720288824992] |