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 | 2 |
| 2 | -7 |
| 3 | 60 |
| 4 | -612 |
| 5 | 6898 |
| 6 | -82806 |
| 7 | 1038076 |
| 8 | -13431940 |
| 9 | 178040315 |
| 10 | -2405137161 |
| 11 | 32992706368 |
| 12 | -458336721104 |
| 13 | 6435090557964 |
| 14 | -91167680664004 |
| 15 | 1301665779507128 |
| 16 | -18710805300530504 |
| 17 | 270559054510943509 |
| 18 | -3932893180646204203 |
| 19 | 57437414168562779574 |
| 20 | -842365843304975785062 |