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 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 120 |
| 6 | 360 |
| 7 | 1680 |
| 8 | 10080 |
| 9 | 72576 |
| 10 | 2419200 |
| 11 | 25660800 |
| 12 | 279417600 |
| 13 | 3286483200 |
| 14 | 41894012160 |
| 15 | 794511244800 |
| 16 | 13755488947200 |
| 17 | 238514695372800 |
| 18 | 4269265386946560 |
| 19 | 79696849513881600 |
| 20 | 1658065431859200000 |