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| n | a(n) |
|---|---|
| 4 | 0 |
| 5 | 1 |
| 6 | 15 |
| 7 | 129 |
| 8 | 891 |
| 9 | 5611 |
| 10 | 34213 |
| 11 | 208230 |
| 12 | 1285094 |
| 13 | 8108722 |
| 14 | 52540098 |
| 15 | 350375379 |
| 16 | 2407395908 |
| 17 | 17048774736 |
| 18 | 124435165429 |
| 19 | 935736058614 |
| 20 | 7246161094614 |
| 21 | 57749473020305 |
| 22 | 473358586652328 |
| 23 | 3987856784525223 |
| 24 | 34506189729577186 |
| 25 | 306454001139880689 |
| 26 | 2791593349164080381 |
[0,1,15,129,891,5611,34213,208230,1285094,8108722, 52540098,350375379,2407395908,17048774736, 124435165429,935736058614,7246161094614, 57749473020305,473358586652328,3987856784525223, 34506189729577186,306454001139880689, 2791593349164080381] |