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 | 4 |
| 3 | -32 |
| 4 | 1936 |
| 5 | -67328 |
| 6 | 4140096 |
| 7 | 353591808 |
| 8 | -262064131840 |
| 9 | 130347373404160 |
| 10 | -65058714844462080 |
| 11 | 36397620373403361280 |
| 12 | -23130160076947953643520 |
| 13 | 16791590408623398030868480 |