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 | 6 |
| 2 | 72 |
| 3 | 738 |
| 4 | 7404 |
| 5 | 74070 |
| 6 | 740736 |
| 7 | 7407402 |
| 8 | 74074068 |
| 9 | 740740734 |
| 10 | 7407407400 |
| 11 | 74074074066 |
| 12 | 740740740732 |
| 13 | 7407407407398 |
| 14 | 74074074074064 |
| 15 | 740740740740730 |
| 16 | 7407407407407396 |
| 17 | 74074074074074062 |
| 18 | 740740740740740728 |
| 19 | 7407407407407407394 |
| 20 | 74074074074074074060 |
| 21 | 740740740740740740726 |