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 | 3 |
| 2 | -9 |
| 3 | 46 |
| 4 | -276 |
| 5 | 1827 |
| 6 | -12838 |
| 7 | 93885 |
| 8 | -706878 |
| 9 | 5440856 |
| 10 | -42608139 |
| 11 | 338345586 |
| 12 | -2717685006 |
| 13 | 22039352340 |
| 14 | -180191062062 |
| 15 | 1483568585389 |
| 16 | -12289222187157 |
| 17 | 102343255814052 |
| 18 | -856335797389803 |
| 19 | 7195400130323322 |
| 20 | -60687964204960104 |
| 21 | 513600833339124915 |