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 | 352800 |
| 10 | 3312000 |
| 11 | 33742080 |
| 12 | 373948416 |
| 13 | 4498421760 |
| 14 | 58506854400 |
| 15 | 819095961600 |
| 16 | 12290021130240 |
| 17 | 194999390208000 |
| 18 | 3294723692298240 |
| 19 | 59059379675381760 |
| 20 | 1119453588069875712 |