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 | -1 |
| 4 | -1 |
| 5 | -1 |
| 6 | 9 |
| 7 | 34 |
| 8 | 90 |
| 9 | -71 |
| 10 | -1645 |
| 11 | -9439 |
| 12 | -25367 |
| 13 | 45902 |
| 14 | 1070146 |
| 15 | 7122361 |
| 16 | 24063637 |
| 17 | -54352333 |
| 18 | -1501032375 |
| 19 | -12319959348 |
| 20 | -53177369044 |
| 21 | 80189626539 |
| 22 | 3910291080509 |
| 23 | 40317032441401 |
| 24 | 228707685648269 |
| 25 | 38882013140648 |
| 26 | -16392939262378536 |