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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 8 |
| 3 | 84 |
| 4 | 1156 |
| 5 | 17122 |
| 6 | 268262 |
| 7 | 4370086 |
| 8 | 73281938 |
| 9 | 1256608767 |
| 10 | 21933420953 |
| 11 | 388400019583 |
| 12 | 6960642974905 |
| 13 | 126008367913375 |
| 14 | 2300862338502425 |
| 15 | 42326714610861679 |
| 16 | 783717720798538121 |
| 17 | 14594469249932149279 |
| 18 | 273161824453612674593 |
| 19 | 5135931850101477641707 |
[1,0,8,84,1156,17122,268262,4370086,73281938, 1256608767,21933420953,388400019583,6960642974905, 126008367913375,2300862338502425, 42326714610861679,783717720798538121, 14594469249932149279,273161824453612674593, 5135931850101477641707] |