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 | 3 |
| 2 | 0 |
| 3 | 9 |
| 4 | -3 |
| 5 | 27 |
| 6 | -18 |
| 7 | 84 |
| 8 | -81 |
| 9 | 270 |
| 10 | -327 |
| 11 | 891 |
| 12 | -1251 |
| 13 | 3000 |
| 14 | -4644 |
| 15 | 10251 |
| 16 | -16932 |
| 17 | 35397 |
| 18 | -61047 |
| 19 | 123123 |
| 20 | -218538 |
| 21 | 430416 |
| 22 | -778737 |
| 23 | 1509786 |
| 24 | -2766627 |
| 25 | 5308095 |
| 26 | -9809667 |
| 27 | 18690912 |
| 28 | -34737096 |
| 29 | 65882403 |
| 30 | -122902200 |
| 31 | 232384305 |
| 32 | -434589003 |
| 33 | 820055115 |
| 34 | -1536151314 |