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 | 4 |
| 3 | 20 |
| 4 | 304 |
| 5 | 6784 |
| 6 | 407684 |
| 7 | 39072966 |
| 8 | 9449433606 |
| 9 | 3830070645700 |
| 10 | 3762885306351756 |
| 11 | 6402694828334379856 |
| 12 | 25695884677997378383120 |