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 | 16 |
| 3 | -96 |
| 4 | 832 |
| 5 | -6528 |
| 6 | 52480 |
| 7 | -419328 |
| 8 | 3355648 |
| 9 | -26843136 |
| 10 | 214749184 |
| 11 | -1717985280 |
| 12 | 13743898624 |
| 13 | -109951156224 |
| 14 | 879609315328 |
| 15 | -7036874391552 |
| 16 | 56294995394560 |
| 17 | -450359962632192 |
| 18 | 3602879702106112 |
| 19 | -28823037614751744 |
| 20 | 230584300922208256 |