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 | 1 |
| 2 | 0 |
| 3 | 1 |
| 4 | -2 |
| 5 | 4 |
| 6 | -17 |
| 7 | 82 |
| 8 | -384 |
| 9 | 2189 |
| 10 | -14850 |
| 11 | 107404 |
| 12 | -845537 |
| 13 | 7400482 |
| 14 | -70093256 |
| 15 | 709888645 |
| 16 | -7721333538 |
| 17 | 89774204756 |
| 18 | -1107347563761 |
| 19 | 14456268008050 |
| 20 | -199350032354000 |
| 21 | 2893615098314941 |
| 22 | -44089764970860290 |
| 23 | 703841452185590236 |
| 24 | -11747695951762870497 |