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 | 7 |
| 2 | 70 |
| 3 | 77 |
| 4 | 700 |
| 5 | 707 |
| 6 | 770 |
| 7 | 777 |
| 8 | 7000 |
| 9 | 7007 |
| 10 | 7070 |
| 11 | 7077 |
| 12 | 7700 |
| 13 | 7707 |
| 14 | 7770 |
| 15 | 7777 |
| 16 | 70000 |
| 17 | 70007 |
| 18 | 70070 |
| 19 | 70077 |
| 20 | 70700 |
| 21 | 70707 |
| 22 | 70770 |
| 23 | 70777 |
| 24 | 77000 |
| 25 | 77007 |
| 26 | 77070 |
| 27 | 77077 |
| 28 | 77700 |
| 29 | 77707 |
| 30 | 77770 |
| 31 | 77777 |
| 32 | 700000 |
| 33 | 700007 |
| 34 | 700070 |
| 35 | 700077 |
| 36 | 700700 |
| 37 | 700707 |
| 38 | 700770 |
| 39 | 700777 |