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 | 0 |
| 1 | 0 |
| 2 | 2 |
| 3 | 6 |
| 4 | 48 |
| 5 | 600 |
| 6 | 10080 |
| 7 | 211680 |
| 8 | 5322240 |
| 9 | 155675520 |
| 10 | 5189184000 |
| 11 | 194075481600 |
| 12 | 8045310873600 |
| 13 | 366061644748800 |
| 14 | 18134130709094400 |
| 15 | 971471287987200000 |
| 16 | 55956746188062720000 |
| 17 | 3448334483839365120000 |