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 | 11 |
| 2 | 101 |
| 3 | 3001 |
| 4 | 70001 |
| 5 | 700001 |
| 6 | 22000001 |
| 7 | 30000001 |
| 8 | 600000001 |
| 9 | 6000000001 |
| 10 | 30000000001 |
| 11 | 1900000000001 |
| 12 | 18000000000001 |
| 13 | 40000000000001 |
| 14 | 3900000000000001 |
| 15 | 6000000000000001 |
| 16 | 130000000000000001 |
| 17 | 3700000000000000001 |
| 18 | 15000000000000000001 |
| 19 | 150000000000000000001 |
| 20 | 600000000000000000001 |
| 21 | 16000000000000000000001 |