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 | -13 |
| 3 | 15 |
| 4 | 1327 |
| 5 | -545 |
| 6 | -91003 |
| 7 | 38255 |
| 8 | 5906767 |
| 9 | -4500801 |
| 10 | -1896209615 |
| 11 | 804237775 |
| 12 | 16784378110837 |
| 13 | -203494252897 |
| 14 | -10883940950701 |
| 15 | 69286348649775 |
| 16 | 359945426905007999 |
| 17 | -30552788046216833 |
| 18 | -279390122489174329921 |
| 19 | 16939504477697671055 |