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 | 4 |
| 3 | 6 |
| 4 | -16 |
| 5 | -124 |
| 6 | -336 |
| 7 | -104 |
| 8 | 2944 |
| 9 | 12816 |
| 10 | 21824 |
| 11 | -40864 |
| 12 | -381696 |
| 13 | -1118144 |
| 14 | -655616 |
| 15 | 8558976 |
| 16 | 40792064 |
| 17 | 77578496 |
| 18 | -97606656 |
| 19 | -1166211584 |
| 20 | -3688779776 |
| 21 | -3093003264 |
| 22 | 24515784704 |
| 23 | 128993171456 |
| 24 | 270814838784 |
| 25 | -206672359424 |
| 26 | -3534837825536 |
| 27 | -12072627707904 |