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 | 2 |
| 2 | 6 |
| 3 | 42 |
| 4 | 1806 |
| 5 | 3263442 |
| 6 | 10650056950806 |
| 7 | 113423713055421844361000442 |
| 8 | 12864938683278671740537145998360961546653259485195806 |