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 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 6 |
| 5 | 9 |
| 6 | 18 |
| 7 | 36 |
| 8 | 72 |
| 9 | 99 |
| 10 | 198 |
| 11 | 396 |
| 12 | 792 |
| 13 | 999 |
| 14 | 1998 |
| 15 | 3996 |
| 16 | 7992 |
| 17 | 9999 |
| 18 | 10989 |
| 19 | 19998 |
| 20 | 21978 |
| 21 | 39996 |
| 22 | 43956 |
| 23 | 76923 |
| 24 | 99999 |
| 25 | 199998 |
| 26 | 399996 |
| 27 | 729927 |
| 28 | 999999 |