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) |
|---|---|
| 0 | 0 |
| 1 | 3 |
| 2 | 6 |
| 3 | 9 |
| 4 | 39 |
| 5 | 69 |
| 6 | 99 |
| 7 | 399 |
| 8 | 699 |
| 9 | 999 |
| 10 | 3999 |
| 11 | 6999 |
| 12 | 9999 |
| 13 | 39999 |
| 14 | 69999 |
| 15 | 99999 |
| 16 | 399999 |
| 17 | 699999 |
| 18 | 999999 |
| 19 | 3999999 |
| 20 | 6999999 |
| 21 | 9999999 |
| 22 | 39999999 |
| 23 | 69999999 |
| 24 | 99999999 |
| 25 | 399999999 |
| 26 | 699999999 |
| 27 | 999999999 |
| 28 | 3999999999 |
| 29 | 6999999999 |
| 30 | 9999999999 |
| 31 | 39999999999 |
| 32 | 69999999999 |