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) |
|---|---|
| 1 | 6 |
| 2 | -12 |
| 3 | 294 |
| 4 | -4800 |
| 5 | 33006 |
| 6 | -868476 |
| 7 | 8045022 |
| 8 | -133497600 |
| 9 | 1840843662 |
| 10 | -23069939772 |
| 11 | 357884304366 |
| 12 | -4506695659200 |
| 13 | 65700186820638 |
| 14 | -892588899692796 |
| 15 | 12240418932523614 |
| 16 | -172125321194572800 |
| 17 | 2335747604463776238 |
| 18 | -32681605781959208508 |
| 19 | 448728077274231515214 |