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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 22 |
| 5 | 225 |
| 6 | 3421 |
| 7 | 73668 |
| 8 | 2222977 |
| 9 | 93033615 |
| 10 | 5393456986 |
| 11 | 433396737873 |
| 12 | 48429436851577 |
| 13 | 7548123580987080 |
| 14 | 1646092439020192801 |
| 15 | 503469306031901522043 |
| 16 | 216430661498688457821022 |
| 17 | 130959358877474026010486145 |
| 18 | 111687660283090149155082836341 |
[1,0,1,3,22,225,3421,73668,2222977,93033615, 5393456986,433396737873,48429436851577, 7548123580987080,1646092439020192801, 503469306031901522043,216430661498688457821022, 130959358877474026010486145, 111687660283090149155082836341] |