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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 144 |
| 3 | 11250688 |
| 4 | 50371911404609819639808 |
| 5 | 58894902159279477652776826941706227937004584169809397602591562463707136 |
[1,4,144,11250688,50371911404609819639808, 58894902159279477652776826941706227937004584169809\ 397602591562463707136] |