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 | 7 |
| 3 | 37 |
| 4 | 73 |
| 5 | 337 |
| 6 | 373 |
| 7 | 733 |
| 8 | 773 |
| 9 | 3373 |
| 10 | 3733 |
| 11 | 7333 |
| 12 | 33377 |
| 13 | 33773 |
| 14 | 37337 |
| 15 | 77377 |
| 16 | 77773 |
| 17 | 333337 |
| 18 | 333737 |
| 19 | 373777 |
| 20 | 377737 |
| 21 | 733333 |
| 22 | 733373 |
| 23 | 737773 |
| 24 | 773777 |
| 25 | 777373 |
| 26 | 777737 |
| 27 | 3333373 |
| 28 | 3333773 |
| 29 | 3337333 |
| 30 | 3337777 |
| 31 | 3377377 |
| 32 | 3733333 |
| 33 | 3773377 |
| 34 | 3773773 |
| 35 | 3777377 |
| 36 | 7337333 |
| 37 | 7337777 |
| 38 | 7377373 |
| 39 | 7733377 |
| 40 | 7737337 |