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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 2 |
| 6 | 8 |
| 7 | 26 |
| 8 | 76 |
| 9 | 212 |
| 10 | 568 |
| 11 | 1504 |
| 12 | 3968 |
| 13 | 10526 |
| 14 | 28192 |
| 15 | 76398 |
| 16 | 209268 |
| 17 | 578396 |
| 18 | 1609376 |
| 19 | 4499336 |
| 20 | 12620080 |
| 21 | 35482718 |
| 22 | 99958776 |
| 23 | 282107702 |
| 24 | 797637908 |
| 25 | 2259545652 |
| 26 | 6413273704 |
| 27 | 18238099464 |
| 28 | 51963195440 |
| 29 | 148315593178 |
| 30 | 424034498656 |
| 31 | 1214186436154 |
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