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 | -1 |
| 5 | 45 |
| 6 | 269 |
| 7 | 147 |
| 8 | -11341 |
| 9 | -101055 |
| 10 | -73711 |
| 11 | 8420247 |
| 12 | 99423719 |
| 13 | 87623445 |
| 14 | -13791067291 |
| 15 | -202300002453 |
| 16 | -202683482821 |
| 17 | 42194985241545 |
| 18 | 738185254885529 |
| 19 | 805294804942047 |
| 20 | -216422419200618961 |
| 21 | -4390167368672158755 |
| 22 | -5040372451183319251 |