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 | 13 |
| 2 | 17 |
| 3 | 19 |
| 4 | 31 |
| 5 | 41 |
| 6 | 61 |
| 7 | 71 |
| 8 | 199 |
| 9 | 313 |
| 10 | 331 |
| 11 | 661 |
| 12 | 881 |
| 13 | 919 |
| 14 | 991 |
| 15 | 1777 |
| 16 | 1999 |
| 17 | 2221 |
| 18 | 3313 |
| 19 | 3331 |
| 20 | 4441 |
| 21 | 6661 |
| 22 | 7177 |
| 23 | 7717 |
| 24 | 9199 |
| 25 | 31333 |
| 26 | 33331 |
| 27 | 71777 |
| 28 | 99991 |
| 29 | 199999 |
| 30 | 313333 |
| 31 | 331333 |
| 32 | 333331 |
| 33 | 991999 |
| 34 | 999199 |
| 35 | 3331333 |
| 36 | 3333133 |
| 37 | 3333313 |
| 38 | 3333331 |
| 39 | 9999991 |
| 40 | 19999999 |