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 | 6 |
| 3 | 36 |
| 4 | 220 |
| 5 | 1365 |
| 6 | 8568 |
| 7 | 54264 |
| 8 | 346104 |
| 9 | 2220075 |
| 10 | 14307150 |
| 11 | 92561040 |
| 12 | 600805296 |
| 13 | 3910797436 |
| 14 | 25518731280 |
| 15 | 166871334960 |
| 16 | 1093260079344 |
| 17 | 7174519270695 |
| 18 | 47153358767970 |
| 19 | 310325523515700 |
| 20 | 2044802197953900 |
| 21 | 13488561475572645 |
| 22 | 89067326568860640 |
| 23 | 588671286046028640 |