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 | 16 |
| 6 | 120 |
| 7 | 720 |
| 8 | 4830 |
| 9 | 31360 |
| 10 | 211680 |
| 11 | 1555200 |
| 12 | 11880000 |
| 13 | 95293440 |
| 14 | 815443200 |
| 15 | 7687680000 |
| 16 | 60432372000 |
| 17 | 530552422400 |
| 18 | 4945330790400 |
| 19 | 51912327168000 |
| 20 | 496766020608000 |
| 21 | 5425624055808000 |
| 22 | 61093281300480000 |
| 23 | 781258429366272000 |
| 24 | 8157685988035584000 |