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 | 0 |
| 2 | 1 |
| 3 | 5 |
| 4 | 31 |
| 5 | 259 |
| 6 | 2801 |
| 7 | 37449 |
| 8 | 597871 |
| 9 | 11111111 |
| 10 | 235794769 |
| 11 | 5628851293 |
| 12 | 149346699503 |
| 13 | 4361070182715 |
| 14 | 139013933454241 |
| 15 | 4803839602528529 |
| 16 | 178901440719363487 |
| 17 | 7143501829211426575 |
| 18 | 304465936543600121441 |