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 | -2 |
| 2 | -2 |
| 3 | 1 |
| 4 | 88 |
| 5 | 583 |
| 6 | 676 |
| 7 | -35597 |
| 8 | -519392 |
| 9 | -3359393 |
| 10 | 19013884 |
| 11 | 896435395 |
| 12 | 13640180896 |
| 13 | 85591357135 |
| 14 | -1527872118356 |
| 15 | -61100053650053 |
| 16 | -1076294742932288 |
| 17 | -7610985095240513 |
| 18 | 200631806070276988 |
| 19 | 9284475508083767059 |
| 20 | 200226297062313730816 |
| 21 | 1940767272243466116463 |