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 | -12 |
| 2 | 84 |
| 3 | -448 |
| 4 | 2004 |
| 5 | -7896 |
| 6 | 28224 |
| 7 | -93312 |
| 8 | 289236 |
| 9 | -848972 |
| 10 | 2377704 |
| 11 | -6391872 |
| 12 | 16571968 |
| 13 | -41599320 |
| 14 | 101430144 |
| 15 | -240877440 |
| 16 | 558440916 |
| 17 | -1266406680 |
| 18 | 2814053908 |
| 19 | -6136337088 |
| 20 | 13148606184 |
| 21 | -27717527552 |