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 | -3 |
| 2 | -7 |
| 3 | -9 |
| 4 | 59 |
| 5 | 483 |
| 6 | -2323 |
| 7 | -42801 |
| 8 | 923923 |
| 9 | 30055311 |
| 10 | -170042041 |
| 11 | -8639161167 |
| 12 | 99976667055 |
| 13 | 7336972779615 |
| 14 | -42962450319915 |
| 15 | -4309733345367105 |
| 16 | 203289825295660035 |
| 17 | 26751125064470578695 |
| 18 | -158415664732997134045 |
| 19 | -26488943422458070446915 |