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 | 1 |
| 3 | -1 |
| 4 | -13 |
| 5 | -49 |
| 6 | 31 |
| 7 | 1981 |
| 8 | 14329 |
| 9 | 2177 |
| 10 | -1138879 |
| 11 | -12745369 |
| 12 | -15140069 |
| 13 | 1638512239 |
| 14 | 25497843007 |
| 15 | 61319246261 |
| 16 | -4755906736399 |
| 17 | -96548141561599 |
| 18 | -363409501289471 |
| 19 | 24376817341458127 |
| 20 | 618727176794661571 |
| 21 | 3242543776104642191 |
| 22 | -201522721892143624609 |