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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 18 |
| 3 | 246 |
| 4 | 3024 |
| 5 | 35244 |
| 6 | 398520 |
| 7 | 4424328 |
| 8 | 48553344 |
| 9 | 528862608 |
| 10 | 5732366112 |
| 11 | 61931306592 |
| 12 | 667638961920 |
| 13 | 7186859400384 |
| 14 | 77287630177152 |
| 15 | 830602309958784 |
| 16 | 8922406425440256 |
| 17 | 95816335481139456 |
| 18 | 1028746337476170240 |
| 19 | 11043759907042186752 |
| 20 | 118545464003618082816 |
[1,18,246,3024,35244,398520,4424328,48553344, 528862608,5732366112,61931306592,667638961920, 7186859400384,77287630177152,830602309958784, 8922406425440256,95816335481139456, 1028746337476170240,11043759907042186752, 118545464003618082816] |