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 | 1 |
| 2 | 4 |
| 3 | 36 |
| 4 | 288 |
| 5 | 36000 |
| 6 | 800 |
| 7 | 1372000 |
| 8 | 2195200 |
| 9 | 2667168000 |
| 10 | 2667168000 |
| 11 | 28400004864 |
| 12 | 3550000608000 |
| 13 | 311974053431040 |
| 14 | 7799351335776000 |
| 15 | 7799351335776000 |
| 16 | 1134451103385600 |
| 17 | 306545704901339904000 |
| 18 | 6812126775585331200 |
| 19 | 233621887768698933504000 |