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 | 6 |
| 4 | 24 |
| 5 | 121 |
| 6 | 722 |
| 7 | 5046 |
| 8 | 40344 |
| 9 | 363000 |
| 10 | 3629521 |
| 11 | 39921843 |
| 12 | 479041932 |
| 13 | 6227383740 |
| 14 | 87181920360 |
| 15 | 1307714287321 |
| 16 | 20923268909764 |
| 17 | 355693655298260 |
| 18 | 6402460885833720 |
| 19 | 121646408103159240 |
| 20 | 2432922931206035521 |
| 21 | 51091297862251106885 |
| 22 | 1124007130194903158430 |