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 | 120 |
| 8 | 840 |
| 9 | 1800 |
| 10 | 6240 |
| 11 | 26760 |
| 12 | 140040 |
| 13 | 867000 |
| 14 | 280080 |
| 15 | 2014080 |
| 16 | 4588320 |
| 17 | 17793120 |
| 18 | 80349120 |
| 19 | 437331840 |
| 20 | 2784689280 |
| 21 | 1311995520 |
| 22 | 9666063360 |
| 23 | 23268113280 |
| 24 | 98802529920 |
| 25 | 465014459520 |
| 26 | 2621479887360 |