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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 1 |
| 4 | 7 |
| 5 | 45 |
| 6 | 465 |
| 7 | 5775 |
| 8 | 88515 |
| 9 | 1588545 |
| 10 | 32852925 |
| 11 | 768242475 |
| 12 | 20053670175 |
| 13 | 577971719325 |
| 14 | 18230691904425 |
| 15 | 624676513836375 |
| 16 | 23106221910646875 |
| 17 | 917643290676737625 |
| 18 | 38944796393877499125 |
| 19 | 1759004961887566267875 |
[1,1,7,45,465,5775,88515,1588545,32852925, 768242475,20053670175,577971719325,18230691904425, 624676513836375,23106221910646875, 917643290676737625,38944796393877499125, 1759004961887566267875] |