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| n | a(n) |
|---|---|
| 0 | 4 |
| 1 | 24 |
| 2 | 216 |
| 3 | 2160 |
| 4 | 32400 |
| 5 | 810000 |
| 6 | 9525600 |
| 7 | 238140000 |
| 8 | 8334900000 |
| 9 | 408410100000 |
| 10 | 6051137400000 |
| 11 | 296505732600000 |
| 12 | 16307815293000000 |
| 13 | 1255701777561000000 |
| 14 | 151939915084881000000 |
| 15 | 1074848105961630000000 |
| 16 | 82763304159045510000000 |
[4,24,216,2160,32400,810000,9525600,238140000, 8334900000,408410100000,6051137400000, 296505732600000,16307815293000000, 1255701777561000000,151939915084881000000, 1074848105961630000000,82763304159045510000000] |