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 | 2 |
| 3 | -9 |
| 4 | 28 |
| 5 | -55 |
| 6 | -234 |
| 7 | 5047 |
| 8 | -59464 |
| 9 | 620433 |
| 10 | -6210710 |
| 11 | 60312791 |
| 12 | -552386988 |
| 13 | 4291343641 |
| 14 | -14786103682 |
| 15 | -469083221865 |
| 16 | 17904311480176 |
| 17 | -458594711604703 |
| 18 | 10473023418660306 |
| 19 | -228670491372982217 |
| 20 | 4899169866194557580 |
| 21 | -104056906653521654679 |
| 22 | 2196053393686810460902 |