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 | 1 |
| 2 | -2 |
| 3 | 18 |
| 4 | -144 |
| 5 | 1900 |
| 6 | -26820 |
| 7 | 485394 |
| 8 | -9679936 |
| 9 | 225394488 |
| 10 | -5765768100 |
| 11 | 164923889350 |
| 12 | -5132384691984 |
| 13 | 174433050454260 |
| 14 | -6385752833589220 |
| 15 | 251596880714336850 |
| 16 | -10585338808667808000 |
| 17 | 474507594337155230704 |
| 18 | -22550580127644413987268 |