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 | 1 |
| 3 | 1 |
| 4 | -24 |
| 5 | 176 |
| 6 | -524 |
| 7 | -5124 |
| 8 | 87126 |
| 9 | -506774 |
| 10 | -1759824 |
| 11 | 57671226 |
| 12 | -358791624 |
| 13 | -2206347624 |
| 14 | 49453238976 |
| 15 | -92944954824 |
| 16 | -4824317301399 |
| 17 | 31062072140001 |
| 18 | 557647434392001 |
| 19 | -6058153265478399 |
| 20 | -93734220877891074 |
| 21 | 1402372000511972226 |
| 22 | 21436083233577492876 |