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 | 1 |
| 2 | 12 |
| 3 | 90 |
| 4 | 1680 |
| 5 | 6300 |
| 6 | 83160 |
| 7 | 1261260 |
| 8 | 576576 |
| 9 | 11027016 |
| 10 | 1163962800 |
| 11 | 1280359080 |
| 12 | 32125373280 |
| 13 | 174012438600 |
| 14 | 80313433200 |
| 15 | 2495453103000 |
| 16 | 165032631878400 |
| 17 | 175347171370800 |
| 18 | 1299631976042400 |
| 19 | 50757848842100400 |
| 20 | 53429314570632000 |
| 21 | 2300131992265707600 |