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 | 9 |
| 2 | 81 |
| 3 | 351 |
| 4 | 1953 |
| 5 | 9999 |
| 6 | 52821 |
| 7 | 275769 |
| 8 | 1446381 |
| 9 | 7572429 |
| 10 | 39673377 |
| 11 | 207796977 |
| 12 | 1088500725 |
| 13 | 5701622643 |
| 14 | 29865934989 |
| 15 | 156441006369 |
| 16 | 819457342785 |
| 17 | 4292413923915 |
| 18 | 22484179383741 |
| 19 | 117774808544331 |
| 20 | 616918515422625 |