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 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 720 |
| 7 | 5040 |
| 8 | 40320 |
| 9 | 322560 |
| 10 | 2943360 |
| 11 | 30078720 |
| 12 | 339696000 |
| 13 | 4196666880 |
| 14 | 56255149440 |
| 15 | 812752093440 |
| 16 | 12585067447680 |
| 17 | 194465276369280 |
| 18 | 3220308737573760 |
| 19 | 56845456896816000 |
| 20 | 1064856592650695040 |
| 21 | 21087473349235547520 |
| 22 | 440007278378842984320 |