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 | 4320 |
| 8 | 30960 |
| 9 | 256320 |
| 10 | 2399760 |
| 11 | 25022880 |
| 12 | 287250480 |
| 13 | 3284869680 |
| 14 | 41344521840 |
| 15 | 566715682800 |
| 16 | 8391341277360 |
| 17 | 133348995238320 |
| 18 | 2262083352430320 |
| 19 | 38232720235613520 |
| 20 | 689864650481977200 |
| 21 | 13221780471876281040 |
| 22 | 268029961230742291440 |