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 | -2 |
| 2 | -2 |
| 3 | 22 |
| 4 | 94 |
| 5 | -890 |
| 6 | -9170 |
| 7 | 67030 |
| 8 | 1495870 |
| 9 | -6581210 |
| 10 | -362016050 |
| 11 | 194447350 |
| 12 | 120002960350 |
| 13 | 554823694150 |
| 14 | -51277487618450 |
| 15 | -601106981110250 |
| 16 | 26775789844186750 |
| 17 | 591304973974171750 |
| 18 | -16113120605399179250 |