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 | -3 |
| 3 | 9 |
| 4 | -32 |
| 5 | 148 |
| 6 | -853 |
| 7 | 6027 |
| 8 | -49576 |
| 9 | 470624 |
| 10 | -5005137 |
| 11 | 59454923 |
| 12 | -774282632 |
| 13 | 11035740844 |
| 14 | -169997137269 |
| 15 | 2826070412955 |
| 16 | -50256453936368 |
| 17 | 954657085889760 |
| 18 | -19247168446169665 |
| 19 | 411277539407862707 |
| 20 | -9269937746437524256 |
| 21 | 220085825544691181500 |
| 22 | -5483977295221312280757 |