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 | -3 |
| 3 | 13 |
| 4 | -103 |
| 5 | 1241 |
| 6 | -19691 |
| 7 | 384805 |
| 8 | -8918351 |
| 9 | 238966705 |
| 10 | -7265920339 |
| 11 | 247123552061 |
| 12 | -9295263915191 |
| 13 | 383095792217737 |
| 14 | -17167554097899323 |
| 15 | 831082449069928021 |
| 16 | -43221681697593767071 |
| 17 | 2403219105771778162529 |
| 18 | -142263939562414917333155 |