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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 32 |
| 3 | 252 |
| 4 | 2032 |
| 5 | 16292 |
| 6 | 132000 |
| 7 | 1070716 |
| 8 | 8729216 |
| 9 | 71320324 |
| 10 | 584550656 |
[4,32,252,2032,16292,132000,1070716,8729216, 71320324,584550656] |