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 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 720 |
| 7 | 5040 |
| 8 | 40320 |
| 9 | 357840 |
| 10 | 3427200 |
| 11 | 34685280 |
| 12 | 365541120 |
| 13 | 3971615760 |
| 14 | 44181889920 |
| 15 | 500788985760 |
| 16 | 5763231048960 |
| 17 | 67163932069920 |
| 18 | 791030794095360 |
| 19 | 9400660122813120 |
| 20 | 112587818898562560 |