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 | 0 |
| 3 | 0 |
| 4 | -1 |
| 5 | 10 |
| 6 | -85 |
| 7 | 735 |
| 8 | -6734 |
| 9 | 66024 |
| 10 | -693230 |
| 11 | 7774250 |
| 12 | -92754046 |
| 13 | 1172033148 |
| 14 | -15609023066 |
| 15 | 217966080150 |
| 16 | -3173198858894 |
| 17 | 47842246890224 |
| 18 | -740798341880328 |
| 19 | 11644416638285544 |
| 20 | -182433719522266066 |
| 21 | 2752864573552860900 |
| 22 | -36826753489645422050 |