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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 16 |
| 5 | 0 |
| 6 | 80352 |
| 7 | 1359288 |
| 8 | 31404480 |
| 9 | 339256836 |
| 10 | 2527519400 |
| 11 | 14053530964 |
| 12 | 63100177488 |
| 13 | 240356217660 |
| 14 | 803630856504 |
| 15 | 2416671974700 |
| 16 | 6655251717376 |
| 17 | 17015566051020 |
| 18 | 40822003107000 |
| 19 | 92679987456312 |
| 20 | 200490192134800 |