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 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 137 |
| 6 | 102521 |
| 7 | 5067156572650 |
| 8 | 507566352736797478112105408650 |
| 9 | 545815719374972260690482400458116738905180797374198467059067284838 |