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 | 0 |
| 2 | 220 |
| 3 | 7920 |
| 4 | 548460 |
| 5 | 42276960 |
| 6 | 3818372800 |
| 7 | 385303564800 |
| 8 | 42556023409900 |
| 9 | 5056698223684800 |
| 10 | 638162986199119920 |
| 11 | 84683717201322993600 |
| 12 | 11723112517163129913600 |
| 13 | 1682392957299926013542400 |
| 14 | 249030549709148521993536000 |
| 15 | 37864267170542400351711467520 |