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 | -18 |
| 2 | 180 |
| 3 | -1320 |
| 4 | 7902 |
| 5 | -40824 |
| 6 | 188232 |
| 7 | -792000 |
| 8 | 3088980 |
| 9 | -11297546 |
| 10 | 39090312 |
| 11 | -128849976 |
| 12 | 406865880 |
| 13 | -1236379320 |
| 14 | 3629385936 |
| 15 | -10324840512 |
| 16 | 28542038238 |
| 17 | -76852151280 |
| 18 | 201967043260 |
| 19 | -518957929080 |
| 20 | 1305848905416 |