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 | 1 |
| 2 | -3 |
| 3 | 9 |
| 4 | -11 |
| 5 | 1 |
| 6 | 45 |
| 7 | -135 |
| 8 | 229 |
| 9 | -143 |
| 10 | -483 |
| 11 | 2025 |
| 12 | -4139 |
| 13 | 4321 |
| 14 | 3597 |
| 15 | -28071 |
| 16 | 69829 |
| 17 | -97199 |
| 18 | 12285 |
| 19 | 351945 |
| 20 | -1104971 |
| 21 | 1907137 |
| 22 | -1301523 |
| 23 | -3723975 |
| 24 | 16378021 |
| 25 | -34238159 |
| 26 | 37202397 |
| 27 | 25345449 |
| 28 | -224845931 |
| 29 | 573156001 |
| 30 | -820084275 |
| 31 | 167628825 |
| 32 | 2777450629 |
| 33 | -9002867183 |