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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 7 |
| 3 | 28 |
| 4 | 140 |
| 5 | 602 |
| 6 | 2772 |
| 7 | 12166 |
| 8 | 54046 |
| 9 | 236093 |
| 10 | 1030101 |
| 11 | 4458247 |
| 12 | 19223202 |
| 13 | 82448782 |
| 14 | 352247250 |
| 15 | 1498724840 |
| 16 | 6353940527 |
| 17 | 26844401919 |
| 18 | 113051495750 |
| 19 | 474652297902 |
| 20 | 1987159118837 |
| 21 | 8296760311018 |
| 22 | 34551340915438 |
| 23 | 143533939056129 |
| 24 | 594877730354756 |
[1,1,7,28,140,602,2772,12166,54046,236093,1030101, 4458247,19223202,82448782,352247250,1498724840, 6353940527,26844401919,113051495750,474652297902, 1987159118837,8296760311018,34551340915438, 143533939056129,594877730354756] |