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 | -3 |
| 2 | -6 |
| 3 | 28 |
| 4 | 56 |
| 5 | -288 |
| 6 | -576 |
| 7 | 3008 |
| 8 | 6016 |
| 9 | -31488 |
| 10 | -62976 |
| 11 | 329728 |
| 12 | 659456 |
| 13 | -3452928 |
| 14 | -6905856 |
| 15 | 36159488 |
| 16 | 72318976 |
| 17 | -378667008 |
| 18 | -757334016 |
| 19 | 3965452288 |
| 20 | 7930904576 |
| 21 | -41526755328 |
| 22 | -83053510656 |
| 23 | 434873827328 |