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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 630 |
| 3 | 122640 |
| 4 | 5162220 |
| 5 | 93900240 |
| 6 | 1004668770 |
| 7 | 7453000800 |
| 8 | 42288908760 |
| 9 | 195528140640 |
| 10 | 769230769230 |
| 11 | 2655593241840 |
| 12 | 8230246567620 |
| 13 | 23298085122480 |
| 14 | 61054982558010 |
| 15 | 149707312950720 |
| 16 | 346430740566960 |
| 17 | 761890617915840 |
| 18 | 1601766528128550 |
| 19 | 3234844881712080 |
[0,0,630,122640,5162220,93900240,1004668770, 7453000800,42288908760,195528140640,769230769230, 2655593241840,8230246567620,23298085122480, 61054982558010,149707312950720,346430740566960, 761890617915840,1601766528128550,3234844881712080] |