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 | -6 |
| 4 | -84 |
| 5 | 171 |
| 6 | 2940 |
| 7 | -6576 |
| 8 | -124260 |
| 9 | 291321 |
| 10 | 5810120 |
| 11 | -14012244 |
| 12 | -289392508 |
| 13 | 711239741 |
| 14 | 15052561056 |
| 15 | -37498302048 |
| 16 | -808073773572 |
| 17 | 2033589755205 |
| 18 | 44436219882252 |
| 19 | -112715767473482 |
| 20 | -2490257138332712 |
| 21 | 6356863001632326 |
| 22 | 141706826771491368 |