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 | 3121 |
| 2 | 78121 |
| 3 | 30517578121 |
| 4 | 710542735760100185871124267578121 |
| 5 | 413590306276513837435704346034981426782906055450439453121 |