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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 4 |
| 3 | 16 |
| 4 | 976 |
| 5 | 662704 |
| 6 | 269896807264 |
| 7 | 124883600543123110859968 |
| 8 | 108643488775144622666209173128243503963147630528 |
[2,4,16,976,662704,269896807264, 124883600543123110859968, 108643488775144622666209173128243503963147630528] |