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 | 56 |
| 5 | 0 |
| 6 | 54972 |
| 7 | 764596 |
| 8 | 8972896 |
| 9 | 62560728 |
| 10 | 322246800 |
| 11 | 1323868260 |
| 12 | 4595943336 |
| 13 | 14000143196 |
| 14 | 38413461800 |
| 15 | 96746410800 |
| 16 | 226834407552 |
| 17 | 500492572112 |
| 18 | 1048044384360 |
| 19 | 2096986629308 |
| 20 | 4031211268200 |