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 | -4 |
| 3 | 41 |
| 4 | -514 |
| 5 | 7206 |
| 6 | -108174 |
| 7 | 1700721 |
| 8 | -27646234 |
| 9 | 460887086 |
| 10 | -7836596944 |
| 11 | 135380098426 |
| 12 | -2369445113804 |
| 13 | 41925242220616 |
| 14 | -748729419265314 |
| 15 | 13478117036893281 |
| 16 | -244306305241572474 |
| 17 | 4455242518055441046 |
| 18 | -81683397232911983784 |
| 19 | 1504758636166747742286 |