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 | -2 |
| 3 | 1 |
| 4 | 10 |
| 5 | -38 |
| 6 | 28 |
| 7 | 289 |
| 8 | -1262 |
| 9 | 1054 |
| 10 | 11044 |
| 11 | -51302 |
| 12 | 45604 |
| 13 | 482068 |
| 14 | -2319176 |
| 15 | 2140129 |
| 16 | 22753378 |
| 17 | -111964106 |
| 18 | 105927508 |
| 19 | 1130780062 |
| 20 | -5652760340 |
| 21 | 5444054956 |
| 22 | 58291068808 |
| 23 | -294808277414 |
| 24 | 287740874260 |
| 25 | 3088109246572 |
| 26 | -15758505143192 |
| 27 | 15541351662484 |
| 28 | 167103084713608 |