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 | 6 |
| 3 | -14 |
| 4 | 38 |
| 5 | -94 |
| 6 | 246 |
| 7 | -622 |
| 8 | 1606 |
| 9 | -4094 |
| 10 | 10518 |
| 11 | -26894 |
| 12 | 68966 |
| 13 | -176542 |
| 14 | 452406 |
| 15 | -1158574 |
| 16 | 2968198 |
| 17 | -7602494 |
| 18 | 19475286 |
| 19 | -49885262 |
| 20 | 127786406 |
| 21 | -327327454 |
| 22 | 838473078 |
| 23 | -2147782894 |
| 24 | 5501675206 |
| 25 | -14092806782 |
| 26 | 36099507606 |
| 27 | -92470734734 |