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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | -3 |
| 5 | 0 |
| 6 | -12 |
| 7 | -12 |
| 8 | -36 |
| 9 | -108 |
| 10 | -210 |
| 11 | -480 |
| 12 | -1746 |
| 13 | -2340 |
| 14 | -10566 |
| 15 | -19500 |
| 16 | -53976 |
| 17 | -152604 |
| 18 | -329424 |
| 19 | -971304 |
| 20 | -2403291 |
| 21 | -5955576 |
| 22 | -16858584 |
| 23 | -40337376 |
| 24 | -110301321 |
| 25 | -287061696 |
| 26 | -730223208 |
| 27 | -1985703720 |
| 28 | -5070001716 |