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 | 2 |
| 3 | 18 |
| 4 | 135 |
| 5 | 1013 |
| 6 | 8458 |
| 7 | 72257 |
| 8 | 628206 |
| 9 | 5556434 |
| 10 | 49815418 |
| 11 | 451476802 |
| 12 | 4128049326 |
| 13 | 38024311091 |
| 14 | 352446754137 |
| 15 | 3284400373590 |
| 16 | 30749731897370 |
| 17 | 289066731934716 |
| 18 | 2727216210298152 |
| 19 | 25812680778645432 |
| 20 | 245015325044029789 |
| 21 | 2331718909954888809 |
| 22 | 22242097596092999144 |