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 | 1 |
| 2 | -3 |
| 3 | 7 |
| 4 | -77 |
| 5 | 231 |
| 6 | -1463 |
| 7 | 4807 |
| 8 | -129789 |
| 9 | 447051 |
| 10 | -3129357 |
| 11 | 11094993 |
| 12 | -159028233 |
| 13 | 574948227 |
| 14 | -4188908511 |
| 15 | 15359331207 |
| 16 | -906200541213 |
| 17 | 3358272593907 |
| 18 | -25000473754641 |
| 19 | 93422822977869 |
| 20 | -1401342344668035 |
| 21 | 5271716439465465 |
| 22 | -39777496770512145 |
| 23 | 150462705175415505 |
| 24 | -4564035390320936985 |