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 | 15 |
| 4 | -82 |
| 5 | 484 |
| 6 | -2992 |
| 7 | 19110 |
| 8 | -124979 |
| 9 | 832234 |
| 10 | -5621028 |
| 11 | 38402783 |
| 12 | -264858143 |
| 13 | 1841221687 |
| 14 | -12886279885 |
| 15 | 90713376563 |
| 16 | -641815393278 |
| 17 | 4561172770669 |
| 18 | -32542369727538 |
| 19 | 232992967457839 |