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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 9 |
| 5 | 128 |
| 6 | 675 |
| 7 | 2048 |
| 8 | 3675 |
| 9 | 262144 |
| 10 | 3472875 |
| 11 | 8388608 |
| 12 | 151278435 |
| 13 | 268435456 |
| 14 | 6249480237 |
| 15 | 4294967296 |
| 16 | 124351902675 |
| 17 | 2199023255552 |
| 18 | 15401871374175 |
| 19 | 140737488355328 |
| 20 | 5834647198969875 |
| 21 | 4503599627370496 |
[1,1,4,9,128,675,2048,3675,262144,3472875,8388608, 151278435,268435456,6249480237,4294967296, 124351902675,2199023255552,15401871374175, 140737488355328,5834647198969875,4503599627370496] |