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 | 0 |
| 3 | 22 |
| 4 | -48 |
| 5 | -722 |
| 6 | 5160 |
| 7 | 39142 |
| 8 | -731808 |
| 9 | -1875362 |
| 10 | 138079320 |
| 11 | -428616938 |
| 12 | -32571174768 |
| 13 | 360902614798 |
| 14 | 8748630825480 |
| 15 | -218739750924218 |
| 16 | -2165282730308928 |
| 17 | 135578968355309758 |
| 18 | -45942716160492360 |
| 19 | -89526354705694434698 |
| 20 | 1011199293695966345712 |