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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 10 |
| 3 | 33 |
| 4 | 110 |
| 5 | 366 |
| 6 | 1220 |
| 7 | 4065 |
| 8 | 13550 |
| 9 | 45162 |
| 10 | 150540 |
| 11 | 501786 |
| 12 | 1672620 |
| 13 | 5575356 |
| 14 | 18584520 |
| 15 | 61948257 |
| 16 | 206494190 |
| 17 | 688313490 |
| 18 | 2294378300 |
| 19 | 7647926046 |
| 20 | 25493086820 |
| 21 | 84976950468 |
| 22 | 283256501560 |
| 23 | 944188318938 |
| 24 | 3147294396460 |
[1,3,10,33,110,366,1220,4065,13550,45162,150540, 501786,1672620,5575356,18584520,61948257, 206494190,688313490,2294378300,7647926046, 25493086820,84976950468,283256501560,944188318938, 3147294396460] |