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| n | a(n) |
|---|---|
| 3 | 1 |
| 4 | 3 |
| 5 | 50 |
| 6 | 270 |
| 7 | 602 |
| 8 | 5376 |
| 9 | 139714 |
| 10 | 1366016 |
| 11 | 15302031 |
| 12 | 161855232 |
| 13 | 2600075865 |
| 14 | 24776769024 |
| 15 | 83295229293 |
| 16 | 1553561635125 |
| 17 | 93399961380678 |
| 18 | 2499411984278178 |
| 19 | 42789384888638364 |
| 20 | 1138928547765375000 |
| 21 | 15344070225505482050 |
| 22 | 450745170646586005994 |
| 23 | 6999343174293499456470 |
[1,3,50,270,602,5376,139714,1366016,15302031, 161855232,2600075865,24776769024,83295229293, 1553561635125,93399961380678,2499411984278178, 42789384888638364,1138928547765375000, 15344070225505482050,450745170646586005994, 6999343174293499456470] |