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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 18 |
| 3 | 252 |
| 4 | 3168 |
| 5 | 37512 |
| 6 | 427608 |
| 7 | 4748472 |
| 8 | 51736248 |
| 9 | 555626232 |
| 10 | 5900636088 |
| 11 | 62105724792 |
| 12 | 648951523128 |
| 13 | 6740563708152 |
| 14 | 69665073373368 |
| 15 | 716985660360312 |
| 16 | 7352870943242808 |
| 17 | 75175838489185272 |
| 18 | 766582546402667448 |
[1,18,252,3168,37512,427608,4748472,51736248, 555626232,5900636088,62105724792,648951523128, 6740563708152,69665073373368,716985660360312, 7352870943242808,75175838489185272, 766582546402667448] |