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 | -11 |
| 5 | -239 |
| 6 | -179 |
| 7 | 24991 |
| 8 | 192025 |
| 9 | -3955391 |
| 10 | -89483399 |
| 11 | 552615031 |
| 12 | 46231717621 |
| 13 | 254468241457 |
| 14 | -26683006147979 |
| 15 | -571848064714289 |
| 16 | 14926049610344881 |
| 17 | 825004339886219521 |
| 18 | -2973711136010539535 |
| 19 | -1134313888244827421465 |
| 20 | -17734152216328857754739 |