This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| 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 |