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 | -6 |
| 3 | -27 |
| 4 | 0 |
| 5 | 1215 |
| 6 | 12312 |
| 7 | 45927 |
| 8 | -657072 |
| 9 | -15857937 |
| 10 | -167699160 |
| 11 | -266960529 |
| 12 | 29356170984 |
| 13 | 700068823623 |
| 14 | 8419188469104 |
| 15 | -1491045413265 |
| 16 | -2856006296224992 |
| 17 | -79065447339366945 |
| 18 | -1162293393139510824 |
| 19 | -744123842820101745 |
| 20 | 538503788896323210360 |