| n | a(n) |
|---|---|
| 1 | 720 |
| 2 | 51840 |
| 3 | 979200 |
| 4 | 9360000 |
| 5 | 276595200 |
| 6 | 1056706560 |
| 7 | 3443212800 |
| 8 | 25721308800 |
| 9 | 137037962880 |
| 10 | 1095199948800 |
| 11 | 2008994088960 |
| 12 | 6114035779200 |
| 13 | 41348052472320 |
| 14 | 95214600000000 |
| 15 | 205608315669120 |
| 16 | 420206392771200 |
| 17 | 818774509363200 |
| 18 | 1124799322521600 |
| 19 | 4805069329111680 |
| 20 | 13414669637644800 |
[720,51840,979200,9360000,276595200,1056706560, 3443212800,25721308800,137037962880,1095199948800, 2008994088960,6114035779200,41348052472320, 95214600000000,205608315669120,420206392771200, 818774509363200,1124799322521600,4805069329111680, 13414669637644800] |