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 | 3 |
| 3 | 10 |
| 4 | 40 |
| 5 | 192 |
| 6 | 1092 |
| 7 | 7248 |
| 8 | 55296 |
| 9 | 478080 |
| 10 | 4625280 |
| 11 | 49524480 |
| 12 | 581368320 |
| 13 | 7422589440 |
| 14 | 102372076800 |
| 15 | 1516402944000 |
| 16 | 24004657152000 |
| 17 | 404347023360000 |
| 18 | 7220327288832000 |
| 19 | 136227009945600000 |
| 20 | 2707657158721536000 |
| 21 | 56546150835879936000 |
| 22 | 1237826569587277824000 |