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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | -10 |
| 6 | 85 |
| 7 | -700 |
| 8 | 5565 |
| 9 | -39270 |
| 10 | 163625 |
| 11 | 2002000 |
| 12 | -80455375 |
| 13 | 1796144350 |
| 14 | -33225267075 |
| 15 | 532997965500 |
| 16 | -6863056074875 |
| 17 | 39757008541250 |
| 18 | 1589961504756625 |
| 19 | -87655679826715000 |
| 20 | 2971557080832965625 |
| 21 | -82299265240798856250 |
| 22 | 1913986621864144953125 |