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 | 4 |
| 4 | 12 |
| 5 | 24 |
| 6 | 72 |
| 7 | 192 |
| 8 | 720 |
| 9 | 1440 |
| 10 | 4320 |
| 11 | 11520 |
| 12 | 43200 |
| 13 | 103680 |
| 14 | 362880 |
| 15 | 1105920 |
| 16 | 4665600 |
| 17 | 9331200 |
| 18 | 27993600 |
| 19 | 74649600 |
| 20 | 279936000 |
| 21 | 671846400 |
| 22 | 2351462400 |
| 23 | 7166361600 |
| 24 | 30233088000 |
| 25 | 67184640000 |
| 26 | 221709312000 |
| 27 | 644972544000 |