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 | 123 |
| 2 | 1234 |
| 3 | 1234567 |
| 4 | 12345678910111213141516171819202122232425262728293031323334 |