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 | -2 |
| 3 | 10 |
| 4 | -77 |
| 5 | 787 |
| 6 | -9972 |
| 7 | 150552 |
| 8 | -2637729 |
| 9 | 52615903 |
| 10 | -1177590290 |
| 11 | 29228602546 |
| 12 | -796945212035 |
| 13 | 23681656958269 |
| 14 | -761803800466856 |
| 15 | 26376749702235900 |
| 16 | -978091742247376932 |
| 17 | 38674335439691203644 |
| 18 | -1624351949069462807480 |
| 19 | 72221688529265896447384 |