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 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 16 |
| 5 | 200 |
| 6 | 2320 |
| 7 | 26460 |
| 8 | 303968 |
| 9 | 3557904 |
| 10 | 42676320 |
| 11 | 526076100 |
| 12 | 6673368240 |
| 13 | 87148818328 |
| 14 | 1171554274800 |
| 15 | 16206294360620 |
| 16 | 230561544221120 |
| 17 | 3371256518888480 |
| 18 | 50628767109223872 |
| 19 | 780358333403627796 |