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 | 3 |
| 2 | 12 |
| 3 | 27 |
| 4 | -75 |
| 5 | -444 |
| 6 | 4734 |
| 7 | 11532 |
| 8 | -466782 |
| 9 | 1626750 |
| 10 | 50347410 |
| 11 | -708889296 |
| 12 | -2196754992 |
| 13 | 179878246239 |
| 14 | -1795732735128 |
| 15 | -24691325878980 |
| 16 | 953903679982809 |
| 17 | -7684914725016600 |
| 18 | -226465559200630566 |
| 19 | 7742131606464606525 |
| 20 | -58889021552013912990 |