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 | 1 |
| 2 | 0 |
| 3 | -6 |
| 4 | 36 |
| 5 | 50 |
| 6 | -6575 |
| 7 | 145222 |
| 8 | -1489978 |
| 9 | -49083480 |
| 10 | 4200404478 |
| 11 | -182031111702 |
| 12 | 4165517606173 |
| 13 | 176264238017452 |
| 14 | -33427749628678925 |
| 15 | 2913726991238703330 |
| 16 | -165770248921085801710 |
| 17 | 1422295225609567363172 |
| 18 | 1326793746164926878993976 |