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 | 2 |
| 3 | -12 |
| 4 | 122 |
| 5 | -1620 |
| 6 | 26882 |
| 7 | -536172 |
| 8 | 12506762 |
| 9 | -334261380 |
| 10 | 10075002962 |
| 11 | -338180323932 |
| 12 | 12512502202202 |
| 13 | -505992958647540 |
| 14 | 22204726014875042 |
| 15 | -1050993549782729292 |
| 16 | 53373431773793542442 |
| 17 | -2894886293042487680100 |
| 18 | 167021024758368026331122 |