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 | -7 |
| 2 | 61 |
| 3 | -21 |
| 4 | 91 |
| 5 | 49 |
| 6 | 5797 |
| 7 | -1981 |
| 8 | -23549 |
| 9 | 88389 |
| 10 | 15037841 |
| 11 | -6154841 |
| 12 | -10416994799 |
| 13 | 607884329 |
| 14 | 13199705491 |
| 15 | -80834386101 |
| 16 | -34108052671693 |
| 17 | 13923204233869 |
| 18 | 51709981061329183 |
| 19 | -3015393801263761 |
| 20 | -1029159167703793759 |
| 21 | 801997872697905009 |
| 22 | 629565265428734688053 |