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 | -4 |
| 4 | -20 |
| 5 | -8 |
| 6 | 184 |
| 7 | 464 |
| 8 | -1648 |
| 9 | -10720 |
| 10 | 8224 |
| 11 | 230848 |
| 12 | 280768 |
| 13 | -4978816 |
| 14 | -17257600 |
| 15 | 104891648 |
| 16 | 727511296 |
| 17 | -1901510144 |
| 18 | -28538404352 |
| 19 | 11377556480 |
| 20 | 1107214478336 |
| 21 | 1759326697472 |
| 22 | -42984354695168 |
| 23 | -163379084079104 |