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 | -1 |
| 2 | 0 |
| 3 | 3 |
| 4 | -5 |
| 5 | -17 |
| 6 | 103 |
| 7 | 55 |
| 8 | -2680 |
| 9 | 6720 |
| 10 | 82446 |
| 11 | -642698 |
| 12 | -2087303 |
| 13 | 53641331 |
| 14 | -96015983 |
| 15 | -4454066000 |
| 16 | 35131380473 |
| 17 | 323923309109 |
| 18 | -6776856484915 |
| 19 | -3620043398324 |
| 20 | 1159030195119059 |
| 21 | -7865002945782432 |
| 22 | -175052008152354596 |
| 23 | 3163635176513031787 |