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 | 0 |
| 3 | -54 |
| 4 | -1024 |
| 5 | -12500 |
| 6 | 0 |
| 7 | 6588344 |
| 8 | 268435456 |
| 9 | 6198727824 |
| 10 | 0 |
| 11 | -9129973459552 |
| 12 | -570630428688384 |
| 13 | -19384006821904192 |
| 14 | 0 |
| 15 | 56050417968750000000 |
| 16 | 4722366482869645213696 |
| 17 | 211773507042902211629312 |
| 18 | 0 |
| 19 | -1012950863698080557631477248 |
| 20 | -107374182400000000000000000000 |