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 | -4 |
| 2 | -8 |
| 3 | 224 |
| 4 | -1184 |
| 5 | -2944 |
| 6 | 84736 |
| 7 | -467968 |
| 8 | -1235456 |
| 9 | 35956736 |
| 10 | -202108928 |
| 11 | -548651008 |
| 12 | 16063381504 |
| 13 | -91151859712 |
| 14 | -251452325888 |
| 15 | 7389369073664 |
| 16 | -42180470767616 |
| 17 | -117581870006272 |
| 18 | 3464100777558016 |
| 19 | -19854347412176896 |
| 20 | -55753417460547584 |
| 21 | 1645577388148391936 |