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 | -2 |
| 5 | -20 |
| 6 | 74 |
| 7 | 98 |
| 8 | -1532 |
| 9 | 960 |
| 10 | 41324 |
| 11 | -105732 |
| 12 | -1595912 |
| 13 | 7998640 |
| 14 | 85401224 |
| 15 | -705417112 |
| 16 | -6026865392 |
| 17 | 76352075520 |
| 18 | 537223559024 |
| 19 | -10130428275792 |
| 20 | -58185728893472 |
| 21 | 1628892022801600 |
| 22 | 7352490891960224 |
| 23 | -313251680404802272 |
| 24 | -1026222973696521152 |