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) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 12 |
| 3 | 72 |
| 4 | 720 |
| 5 | 12960 |
| 6 | 440640 |
| 7 | 29082240 |
| 8 | 3780691200 |
| 9 | 975418329600 |
| 10 | 501365021414400 |
| 11 | 514400511971174400 |
| 12 | 1054521049540907520000 |
| 13 | 4321427261018639016960000 |
| 14 | 35409774976786728104970240000 |
| 15 | 580224572769627326728042352640000 |