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 | -1 |
| 2 | -1 |
| 3 | 2 |
| 4 | 0 |
| 5 | 29 |
| 6 | -135 |
| 7 | 727 |
| 8 | -1967 |
| 9 | -6074 |
| 10 | 94510 |
| 11 | 1548051 |
| 12 | -41361089 |
| 13 | 408842095 |
| 14 | 213929807 |
| 15 | -41951737904 |
| 16 | 130060640466 |
| 17 | 10569226878107 |
| 18 | -229371598130229 |
| 19 | 3327344803563111 |
| 20 | -31418096993670379 |
| 21 | -383829978086171112 |
| 22 | 17799865170898698140 |
| 23 | 220582224147105677385 |