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 | 0 |
| 1 | -2 |
| 2 | -2 |
| 3 | 6 |
| 4 | 14 |
| 5 | -34 |
| 6 | -138 |
| 7 | 310 |
| 8 | 1918 |
| 9 | -4146 |
| 10 | -36154 |
| 11 | 76454 |
| 12 | 891342 |
| 13 | -1859138 |
| 14 | -27891050 |
| 15 | 57641238 |
| 16 | 1080832286 |
| 17 | -2219305810 |
| 18 | -50833628826 |
| 19 | 103886563462 |
| 20 | 2853207760750 |
| 21 | -5810302084962 |
| 22 | -188424521441482 |
| 23 | 382659344967926 |
| 24 | 14464296482284734 |
| 25 | -29311252309537394 |
| 26 | -1277229462293249018 |