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 | 0 |
| 3 | 6 |
| 4 | 48 |
| 5 | 360 |
| 6 | 2880 |
| 7 | 25200 |
| 8 | 241920 |
| 9 | 2540160 |
| 10 | 29030400 |
| 11 | 359251200 |
| 12 | 4790016000 |
| 13 | 68497228800 |
| 14 | 1046139494400 |
| 15 | 16999766784000 |
| 16 | 292919058432000 |
| 17 | 5335311421440000 |
| 18 | 102437979291648000 |
| 19 | 2067966706950144000 |