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 | 0 |
| 3 | 0 |
| 4 | 4 |
| 5 | -1 |
| 6 | -9 |
| 7 | 103 |
| 8 | -132 |
| 9 | -535 |
| 10 | 7731 |
| 11 | -25117 |
| 12 | -18072 |
| 13 | 1078215 |
| 14 | -6917039 |
| 15 | 16312667 |
| 16 | 186611792 |
| 17 | -2454241183 |
| 18 | 14370311311 |
| 19 | 1436259867 |
| 20 | -934228834216 |
| 21 | 10658996229479 |
| 22 | -54990712418263 |
| 23 | -185381404760729 |
| 24 | 7270919988375200 |
| 25 | -80130195880201583 |
| 26 | 391992372213719679 |