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 | 27 |
| 3 | -189 |
| 4 | 1377 |
| 5 | -9963 |
| 6 | 72171 |
| 7 | -522693 |
| 8 | 3785697 |
| 9 | -27418419 |
| 10 | 198581787 |
| 11 | -1438256493 |
| 12 | 10416775041 |
| 13 | -75444958683 |
| 14 | 546420727467 |
| 15 | -3957528992949 |
| 16 | 28662960504897 |
| 17 | -207595523965923 |
| 18 | 1503539788339611 |
| 19 | -10889598445730973 |
| 20 | 78869448769442337 |
| 21 | -571223078628232779 |