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 | 1 |
| 1 | 2 |
| 2 | 21 |
| 3 | 301 |
| 4 | 4001 |
| 5 | 50001 |
| 6 | 600001 |
| 7 | 7000001 |
| 8 | 80000001 |
| 9 | 900000001 |
| 10 | 10000000001 |
| 11 | 110000000001 |
| 12 | 1200000000001 |
| 13 | 13000000000001 |
| 14 | 140000000000001 |
| 15 | 1500000000000001 |
| 16 | 16000000000000001 |
| 17 | 170000000000000001 |
| 18 | 1800000000000000001 |
| 19 | 19000000000000000001 |