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 | 300 |
| 3 | 903 |
| 4 | 990 |
| 5 | 3003 |
| 6 | 33930 |
| 7 | 39903 |
| 8 | 339900 |
| 9 | 930930 |
| 10 | 39033030 |
| 11 | 990903903 |
| 12 | 3909003990 |
| 13 | 3993990000 |
| 14 | 33003300903 |
| 15 | 39999939903 |
| 16 | 90993993300 |
| 17 | 3390003090090 |
| 18 | 99990099000330 |
| 19 | 90009933903093903 |
| 20 | 399939399933939330 |
| 21 | 303300903903330099003 |
| 22 | 3309000900300303999300 |