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 | 0 |
| 1 | 1 |
| 2 | -4 |
| 3 | 24 |
| 4 | -128 |
| 5 | 704 |
| 6 | -3840 |
| 7 | 20992 |
| 8 | -114688 |
| 9 | 626688 |
| 10 | -3424256 |
| 11 | 18710528 |
| 12 | -102236160 |
| 13 | 558628864 |
| 14 | -3052404736 |
| 15 | 16678649856 |
| 16 | -91133837312 |
| 17 | 497964548096 |
| 18 | -2720928890880 |
| 19 | 14867431948288 |
| 20 | -81237158920192 |
| 21 | 443888091267072 |
| 22 | -2425449636429824 |
| 23 | 13252903275855872 |