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 | -4 |
| 2 | 24 |
| 3 | -104 |
| 4 | 584 |
| 5 | -2664 |
| 6 | 14344 |
| 7 | -67624 |
| 8 | 354504 |
| 9 | -1706984 |
| 10 | 8797064 |
| 11 | -42936744 |
| 12 | 218878024 |
| 13 | -1077612904 |
| 14 | 5455173384 |
| 15 | -27007431464 |
| 16 | 136110899144 |
| 17 | -676259528424 |
| 18 | 3398477511304 |
| 19 | -16923668079784 |