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) |
|---|---|
| 1 | 1 |
| 2 | -2 |
| 3 | 7 |
| 4 | -26 |
| 5 | 107 |
| 6 | -468 |
| 7 | 2141 |
| 8 | -10124 |
| 9 | 49101 |
| 10 | -242934 |
| 11 | 1221427 |
| 12 | -6222838 |
| 13 | 32056215 |
| 14 | -166690696 |
| 15 | 873798681 |
| 16 | -4612654808 |
| 17 | 24499322137 |
| 18 | -130830894666 |
| 19 | 702037771647 |
| 20 | -3783431872018 |
| 21 | 20469182526595 |
| 22 | -111133368084892 |
| 23 | 605312629105205 |
| 24 | -3306633429423460 |
| 25 | 18111655081108453 |