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 | 21 |
| 2 | 211 |
| 3 | 1689 |
| 4 | 84457 |
| 5 | 1689161 |
| 6 | 16891643 |
| 7 | 1351331869 |
| 8 | 2702663881 |
| 9 | 270266390531 |
| 10 | 2702663909509 |
| 11 | 108106556409753 |
| 12 | 1081065564149533 |
| 13 | 4324262256635277 |
| 14 | 43242622566419631 |
| 15 | 6918819610629079929 |