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) |
|---|---|
| 1 | 1 |
| 2 | -1 |
| 3 | 1 |
| 4 | 3 |
| 5 | -38 |
| 6 | 234 |
| 7 | -586 |
| 8 | -9493 |
| 9 | 194906 |
| 10 | -1981880 |
| 11 | 4724642 |
| 12 | 301409600 |
| 13 | -7840250579 |
| 14 | 102256372812 |
| 15 | -9254171165 |
| 16 | -39936103724491 |
| 17 | 1199830608004118 |
| 18 | -17733202003472076 |
| 19 | -96125957089130420 |