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 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 8 |
| 5 | 15 |
| 6 | 24 |
| 7 | 120 |
| 8 | 168 |
| 9 | 840 |
| 10 | 1680 |
| 11 | 5040 |
| 12 | 201600 |
| 13 | 256032000 |