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 | 1 |
| 3 | -3 |
| 4 | 16 |
| 5 | -90 |
| 6 | 616 |
| 7 | -4893 |
| 8 | 44416 |
| 9 | -453540 |
| 10 | 5145856 |
| 11 | -64222983 |
| 12 | 874402816 |
| 13 | -12897183390 |
| 14 | 204862698496 |
| 15 | -3486535686273 |
| 16 | 63292764553216 |
| 17 | -1220795601029640 |
| 18 | 24931903045697536 |
| 19 | -537463528325234763 |