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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 4 |
| 3 | 56 |
| 4 | 1024 |
| 5 | 55390 |
| 6 | 6525374 |
| 7 | 1227812226 |
| 8 | 723886147451 |
| 9 | 1084184652392138 |
[0,4,56,1024,55390,6525374,1227812226, 723886147451,1084184652392138] |