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 | 3 |
| 2 | 13 |
| 3 | 209 |
| 4 | 53505 |
| 5 | 3506503681 |
| 6 | 15060318633198616577 |
| 7 | 277813843495134114797235287762174738433 |
| 8 | 94535152227927400227782074307303551040545228366095741656402842333161034088449 |