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 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 119 |
| 6 | 708 |
| 7 | 4915 |
| 8 | 38992 |
| 9 | 347990 |
| 10 | 3450772 |
| 11 | 37640794 |
| 12 | 447908832 |
| 13 | 5774077131 |
| 14 | 80160465380 |
| 15 | 1192342710241 |
| 16 | 18917802834912 |
| 17 | 318910800658728 |
| 18 | 5692346715440768 |
| 19 | 107249322475436984 |
| 20 | 2127032690422975168 |
| 21 | 44293813329642772714 |
| 22 | 966307529386769800328 |