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 | 5 |
| 5 | 273 |
| 6 | 2982616 |
| 7 | 1830034134296583 |
| 8 | 4219771415190209120329546223112205 |
| 9 | 159545978336249166974717516821935499136450045008874233960892835107904996 |