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 | 21 |
| 3 | 93 |
| 4 | 381 |
| 5 | 24573 |
| 6 | 393213 |
| 7 | 1572861 |
| 8 | 6442450941 |
| 9 | 6917529027641081853 |
| 10 | 1856910058928070412348686333 |
| 11 | 486777830487640090174734030864381 |
| 12 | 510423550381407695195061911147652317181 |