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 | 0 |
| 4 | 0 |
| 5 | 120 |
| 6 | 1440 |
| 7 | 14280 |
| 8 | 141120 |
| 9 | 1462104 |
| 10 | 16148160 |
| 11 | 191051520 |
| 12 | 2421936000 |
| 13 | 32840519712 |
| 14 | 475109002368 |
| 15 | 7312951114560 |
| 16 | 119419875993600 |
| 17 | 2063254247160192 |
| 18 | 37617587514390528 |
| 19 | 721991172931734528 |