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 | -12 |
| 4 | 14 |
| 5 | -24 |
| 6 | 84 |
| 7 | -144 |
| 8 | -42 |
| 9 | 130 |
| 10 | 1656 |
| 11 | -3036 |
| 12 | -9036 |
| 13 | 17784 |
| 14 | 76944 |
| 15 | -147984 |
| 16 | -591274 |
| 17 | 1147068 |
| 18 | 4784922 |
| 19 | -9277164 |
| 20 | -38983272 |
| 21 | 75690528 |
| 22 | 322116804 |
| 23 | -625832880 |
| 24 | -2687394012 |
| 25 | 5224589254 |
| 26 | 22613921832 |
| 27 | -43985741688 |
| 28 | -191670898032 |
| 29 | 372970548504 |
| 30 | 1634759644944 |
| 31 | -3182191744320 |