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 | 0 |
| 2 | -1 |
| 3 | -1 |
| 4 | 17 |
| 5 | 99 |
| 6 | -926 |
| 7 | -20385 |
| 8 | 25969 |
| 9 | 7206059 |
| 10 | 90298826 |
| 11 | -3271747557 |
| 12 | -149187119280 |
| 13 | 236884125841 |
| 14 | 233237751740057 |
| 15 | 7110791842650002 |
| 16 | -293292401726383791 |
| 17 | -32980038867059802549 |
| 18 | -498084376275585698222 |
| 19 | 114298048468067933019627 |
| 20 | 9072219653673352772098960 |