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 | 0 |
| 2 | 7 |
| 3 | -16 |
| 4 | 177 |
| 5 | -1096 |
| 6 | 10975 |
| 7 | -94872 |
| 8 | 1101121 |
| 9 | -11699632 |
| 10 | 151701111 |
| 11 | -1897734400 |
| 12 | 27287272177 |
| 13 | -385421578296 |
| 14 | 6100570870927 |
| 15 | -95315920570696 |
| 16 | 1642003509857025 |
| 17 | -27968228816277472 |
| 18 | 520462884927746791 |
| 19 | -9551232423922438512 |
| 20 | 190797743531054785201 |