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 | 0 |
| 1 | 1 |
| 2 | -3 |
| 3 | 9 |
| 4 | -32 |
| 5 | 140 |
| 6 | -757 |
| 7 | 4963 |
| 8 | -38376 |
| 9 | 341664 |
| 10 | -3438641 |
| 11 | 38576747 |
| 12 | -477118600 |
| 13 | 6447914668 |
| 14 | -94515392805 |
| 15 | 1493405394411 |
| 16 | -25300960235504 |
| 17 | 457490990665952 |
| 18 | -8793604786338049 |
| 19 | 179039287811168755 |
| 20 | -3849069823206873888 |