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A304556 as a simple table
| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 4 |
| 3 | 54 |
| 4 | 928 |
| 5 | 31338 |
| 6 | 2060618 |
| 7 | 266749364 |
| 8 | 68574754440 |
| 9 | 35160711883758 |
[0,4,54,928,31338,2060618,266749364,68574754440, 35160711883758] |