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 | 15 |
| 2 | 51 |
| 3 | 1155 |
| 4 | 1515 |
| 5 | 1551 |
| 6 | 5115 |
| 7 | 5151 |
| 8 | 5511 |
| 9 | 111555 |
| 10 | 115155 |
| 11 | 115515 |
| 12 | 115551 |
| 13 | 151155 |
| 14 | 151515 |
| 15 | 151551 |
| 16 | 155115 |
| 17 | 155151 |
| 18 | 155511 |
| 19 | 511155 |
| 20 | 511515 |
| 21 | 511551 |
| 22 | 515115 |
| 23 | 515151 |
| 24 | 515511 |
| 25 | 551115 |
| 26 | 551151 |
| 27 | 551511 |
| 28 | 555111 |