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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 7 |
| 4 | 36 |
| 5 | 171 |
| 6 | 813 |
| 7 | 4012 |
| 8 | 20891 |
| 9 | 115463 |
| 10 | 677546 |
| 11 | 4211549 |
| 12 | 27640341 |
| 13 | 190891130 |
| 14 | 1382942161 |
| 15 | 10480109379 |
| 16 | 82864804268 |
| 17 | 682076675087 |
| 18 | 5832741942913 |
| 19 | 51724157711084 |
| 20 | 474869815108175 |
| 21 | 4506715736350171 |
| 22 | 44152005850890042 |
| 23 | 445958869286416681 |
| 24 | 4638590332213222137 |
[0,0,1,7,36,171,813,4012,20891,115463,677546, 4211549,27640341,190891130,1382942161,10480109379, 82864804268,682076675087,5832741942913, 51724157711084,474869815108175,4506715736350171, 44152005850890042,445958869286416681, 4638590332213222137] |