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 | 15 |
| 4 | 259 |
| 5 | 1608 |
| 6 | 1582152 |
| 7 | 157042600 |
| 8 | 11778545664 |
| 9 | 3336975844504 |
| 10 | 440384712302421 |