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 | 33331 |
| 2 | 99991 |
| 3 | 242424241 |
| 4 | 404040401 |
| 5 | 454545451 |
| 6 | 464646461 |
| 7 | 494949491 |
| 8 | 525252521 |
| 9 | 575757571 |
| 10 | 737373731 |
| 11 | 787878781 |
| 12 | 949494941 |
| 13 | 1021021021021 |
| 14 | 1081081081081 |
| 15 | 1091091091091 |
| 16 | 1211211211211 |
| 17 | 1291291291291 |
| 18 | 1481481481481 |
| 19 | 1511511511511 |