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 | 0 |
| 2 | 2 |
| 3 | 0 |
| 4 | 24 |
| 5 | -30 |
| 6 | 694 |
| 7 | -1050 |
| 8 | 37832 |
| 9 | -167076 |
| 10 | 3840946 |
| 11 | -16352820 |
| 12 | 484077316 |
| 13 | -3571377810 |
| 14 | 92305923462 |
| 15 | -735565382370 |
| 16 | 24089429290352 |
| 17 | -260389373957160 |
| 18 | 7612771211634930 |
| 19 | -88060997260644552 |
| 20 | 2819270530524656316 |
| 21 | -42624237378570669990 |
| 22 | 1487399781900667121150 |