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 | 0 |
| 6 | 20 |
| 7 | 480 |
| 8 | 4830 |
| 9 | 40320 |
| 10 | 346080 |
| 11 | 3014400 |
| 12 | 28036800 |
| 13 | 271180800 |
| 14 | 2723635200 |
| 15 | 28751923200 |
| 16 | 273405132000 |
| 17 | 2754444492800 |
| 18 | 29222409216000 |
| 19 | 335670386688000 |
| 20 | 3786723502848000 |
| 21 | 45941770321920000 |
| 22 | 580488335032320000 |
| 23 | 8000481890598912000 |