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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 2 |
| 4 | 13 |
| 5 | 64 |
| 6 | 285 |
| 7 | 1210 |
| 8 | 5005 |
| 9 | 20384 |
| 10 | 82212 |
| 11 | 329460 |
| 12 | 1314610 |
| 13 | 5230016 |
| 14 | 20764055 |
| 15 | 82317690 |
| 16 | 326012925 |
| 17 | 1290244800 |
| 18 | 5103910680 |
| 19 | 20183646780 |
| 20 | 79802261190 |
| 21 | 315492902400 |
| 22 | 1247247742650 |
| 23 | 4930910180196 |
| 24 | 19495286167698 |
| 25 | 77085553829824 |
[0,0,2,13,64,285,1210,5005,20384,82212,329460, 1314610,5230016,20764055,82317690,326012925, 1290244800,5103910680,20183646780,79802261190, 315492902400,1247247742650,4930910180196, 19495286167698,77085553829824] |