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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 26 |
| 6 | 264 |
| 7 | 1846 |
| 8 | 10616 |
| 9 | 54354 |
| 10 | 258388 |
| 11 | 1168862 |
| 12 | 5109696 |
| 13 | 21805162 |
| 14 | 91460972 |
| 15 | 378874998 |
| 16 | 1555269016 |
| 17 | 6341845250 |
| 18 | 25732834116 |
| 19 | 104034429454 |
| 20 | 419461348976 |
| 21 | 1687846763418 |
| 22 | 6781455643420 |
| 23 | 27216164395430 |
| 24 | 109135969307976 |
| 25 | 437358413244466 |
| 26 | 1751878519306484 |
| 27 | 7014851306040126 |
| 28 | 28081422396752416 |
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