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 | 1 |
| 3 | 2 |
| 4 | 0 |
| 5 | 44 |
| 6 | 0 |
| 7 | 1224 |
| 8 | 2688 |
| 9 | 25920 |
| 10 | 293760 |
| 11 | 3628800 |
| 12 | 25090560 |
| 13 | 762048000 |
| 14 | 3887170560 |
| 15 | 62749209600 |
| 16 | 1233908121600 |
| 17 | 22616539545600 |
| 18 | 321930878976000 |
| 19 | 10717413809356800 |
| 20 | 108951843667968000 |
| 21 | 1982497256570880000 |
| 22 | 50138292140310528000 |
| 23 | 1408088823809310720000 |
| 24 | 25175914255793258496000 |