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 | 35280 |
| 9 | 287280 |
| 10 | 2656080 |
| 11 | 27422640 |
| 12 | 312273360 |
| 13 | 3884393520 |
| 14 | 52370755920 |
| 15 | 704126188080 |
| 16 | 10259633739600 |
| 17 | 160825241006640 |
| 18 | 2696186419390800 |
| 19 | 48104638617656880 |
| 20 | 909616190783645520 |
| 21 | 18163810790066314800 |
| 22 | 361758057531039101520 |