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 | 7 |
| 2 | 17 |
| 3 | 0 |
| 4 | 1117 |
| 5 | 11117 |
| 6 | 0 |
| 7 | 1111711 |
| 8 | 11111117 |
| 9 | 0 |
| 10 | 1117111111 |
| 11 | 17111111111 |
| 12 | 0 |
| 13 | 1111171111111 |
| 14 | 0 |
| 15 | 0 |
| 16 | 0 |
| 17 | 11111111111111171 |
| 18 | 0 |
| 19 | 1111111111111111171 |
| 20 | 11111111111111117111 |
| 21 | 0 |
| 22 | 1111111111111111111711 |
| 23 | 11111111111111111111117 |