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 | 3 |
| 2 | 13 |
| 3 | 113 |
| 4 | 0 |
| 5 | 11113 |
| 6 | 113111 |
| 7 | 0 |
| 8 | 11111131 |
| 9 | 111111113 |
| 10 | 0 |
| 11 | 11111111113 |
| 12 | 111113111111 |
| 13 | 0 |
| 14 | 31111111111111 |
| 15 | 0 |
| 16 | 0 |
| 17 | 11111111113111111 |
| 18 | 111111111111111131 |
| 19 | 0 |
| 20 | 11111111111111111131 |
| 21 | 131111111111111111111 |
| 22 | 0 |
| 23 | 11111111111111111311111 |