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 | 63 |
| 2 | 1953 |
| 3 | 39711 |
| 4 | 595665 |
| 5 | 7028847 |
| 6 | 67945521 |
| 7 | 553270671 |
| 8 | 3872894697 |
| 9 | 23667689815 |
| 10 | 127805525001 |
| 11 | 615790256823 |
| 12 | 2668424446233 |
| 13 | 10468434365991 |
| 14 | 37387265592825 |
| 15 | 122131734269895 |
| 16 | 366395202809685 |
| 17 | 1012974972473835 |
| 18 | 2588713818544245 |
| 19 | 6131164307078475 |