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) |
|---|---|
| 1 | 1 |
| 2 | -24 |
| 3 | 300 |
| 4 | -2624 |
| 5 | 18126 |
| 6 | -105504 |
| 7 | 538296 |
| 8 | -2471424 |
| 9 | 10400997 |
| 10 | -40674128 |
| 11 | 149343012 |
| 12 | -519045888 |
| 13 | 1718732998 |
| 14 | -5451292992 |
| 15 | 16633756008 |
| 16 | -49010118656 |
| 17 | 139877936370 |
| 18 | -387749049720 |
| 19 | 1046413709980 |
| 20 | -2754808758144 |
| 21 | 7087483527072 |