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 | 11 |
| 3 | 23 |
| 4 | 103 |
| 5 | 113 |
| 6 | 223 |
| 7 | 2237 |
| 8 | 10007 |
| 9 | 10193 |
| 10 | -1 |
| 11 | 11113 |
| 12 | 22273 |
| 13 | 100003 |
| 14 | 166931 |
| 15 | -1 |
| 16 | -1 |
| 17 | 111119 |
| 18 | 222323 |
| 19 | 1000003 |
| 20 | 1367777 |
| 21 | -1 |
| 22 | -1 |
| 23 | -1 |
| 24 | 1111711 |
| 25 | 2222273 |
| 26 | 10000019 |
| 27 | 13334117 |
| 28 | -1 |
| 29 | -1 |
| 30 | -1 |
| 31 | -1 |
| 32 | 11111117 |
| 33 | 22222223 |
| 34 | 100000007 |
| 35 | 110499911 |
| 36 | -1 |
| 37 | -1 |
| 38 | -1 |
| 39 | -1 |
| 40 | -1 |
| 41 | 111111113 |
| 42 | 222222227 |