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 | 1 |
| 2 | 3 |
| 3 | 11 |
| 4 | 51 |
| 5 | 287 |
| 6 | 1899 |
| 7 | 14447 |
| 8 | 124251 |
| 9 | 1192127 |
| 10 | 12623979 |
| 11 | 146250287 |
| 12 | 1840024251 |
| 13 | 24983863967 |
| 14 | 364140992139 |
| 15 | 5670546353807 |
| 16 | 93960923507931 |
| 17 | 1650688221777407 |
| 18 | 30646388716777899 |
| 19 | 599565840087487727 |
| 20 | 12328458398407260411 |