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 | 1 |
| 5 | -4 |
| 6 | 1 |
| 7 | 29 |
| 8 | -167 |
| 9 | 1000 |
| 10 | -7989 |
| 11 | 75857 |
| 12 | -794639 |
| 13 | 9058180 |
| 14 | -111944923 |
| 15 | 1492748581 |
| 16 | -21369667087 |
| 17 | 326932765840 |
| 18 | -5323818187817 |
| 19 | 91947960224097 |
| 20 | -1678914212753599 |
| 21 | 32317295442288844 |
| 22 | -654084630476955479 |
| 23 | 13886774070229667213 |