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 | 7 |
| 2 | -192 |
| 3 | -6049 |
| 4 | -61440 |
| 5 | -357857 |
| 6 | -1417472 |
| 7 | -3667649 |
| 8 | 0 |
| 9 | 91171007 |
| 10 | 973741824 |
| 11 | 8375575711 |
| 12 | 68289495040 |
| 13 | 548940083167 |
| 14 | 4396570722048 |
| 15 | 35181809198207 |
| 16 | 281470681743360 |
| 17 | 2251792837927807 |
| 18 | 18014387489521408 |
| 19 | 144115171092292831 |