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 | -254 |
| 3 | -6555 |
| 4 | -65512 |
| 5 | -390505 |
| 6 | -1678896 |
| 7 | -5759761 |
| 8 | -16736896 |
| 9 | -42683841 |
| 10 | -96371200 |
| 11 | -174442081 |
| 12 | 49019904 |
| 13 | 5411290079 |
| 14 | 85702502144 |
| 15 | 1305111477375 |
| 16 | 20918494920704 |
| 17 | 355680452338559 |
| 18 | 6402362685767424 |
| 19 | 121645083425268959 |
| 20 | 2432901982576640000 |