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 | 2 |
| 3 | 9 |
| 4 | 49 |
| 5 | 322 |
| 6 | 2411 |
| 7 | 19868 |
| 8 | 178832 |
| 9 | 1724689 |
| 10 | 17728545 |
| 11 | 192634930 |
| 12 | 2201760840 |
| 13 | 26341552085 |
| 14 | 328644606302 |
| 15 | 4261866683006 |
| 16 | 57288746422850 |
| 17 | 796337785825197 |
| 18 | 11422744246417607 |
| 19 | 168765251734898485 |
| 20 | 2564015637845130072 |
| 21 | 39998356172536082076 |
| 22 | 639840751503820832346 |