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 | 2 |
| 2 | 6 |
| 3 | 61 |
| 4 | 507 |
| 5 | 1048447 |
| 6 | 134216703 |
| 7 | 1073739775 |
| 8 | 9007199250546687 |
| 9 | 5192296858534827626278696515534847 |
| 10 | 187072209578355573530071658285452771612302071824383 |