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 | 6 |
| 2 | 21 |
| 3 | 129 |
| 4 | 1290 |
| 5 | 20209 |
| 6 | 353018 |
| 7 | 7537961 |
| 8 | 173772587 |
| 9 | 4735433401 |
| 10 | 160157951005 |