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) |
|---|---|
| 1 | 1 |
| 2 | -6 |
| 3 | 43 |
| 4 | -300 |
| 5 | 2101 |
| 6 | -14706 |
| 7 | 102943 |
| 8 | -720600 |
| 9 | 5044201 |
| 10 | -35309406 |
| 11 | 247165843 |
| 12 | -1730160900 |
| 13 | 12111126301 |
| 14 | -84777884106 |
| 15 | 593445188743 |
| 16 | -4154116321200 |
| 17 | 29078814248401 |
| 18 | -203551699738806 |
| 19 | 1424861898171643 |
| 20 | -9974033287201500 |