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 | 12 |
| 3 | -47 |
| 4 | 190 |
| 5 | -778 |
| 6 | 3224 |
| 7 | -13475 |
| 8 | 56710 |
| 9 | -239986 |
| 10 | 1020200 |
| 11 | -4353430 |
| 12 | 18636908 |
| 13 | -80004388 |
| 14 | 344264624 |
| 15 | -1484499811 |
| 16 | 6413133638 |
| 17 | -27750688914 |
| 18 | 120258432264 |
| 19 | -521833284514 |
| 20 | 2267084792708 |
| 21 | -9859984425324 |
| 22 | 42925569027408 |