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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 8 |
| 5 | 59 |
| 6 | 458 |
| 7 | 3865 |
| 8 | 35688 |
| 9 | 360127 |
| 10 | 3956214 |
| 11 | 47096633 |
| 12 | 604722604 |
| 13 | 8337692687 |
| 14 | 122932350162 |
| 15 | 1930964182649 |
| 16 | 32201197533072 |
| 17 | 568323756438079 |
| 18 | 10585305178638446 |
| 19 | 207520767220183033 |
| 20 | 4272031355927379828 |
| 21 | 92145190111463378863 |
| 22 | 2078280173125850650890 |
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