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 | 5 |
| 2 | 10 |
| 3 | 10 |
| 4 | 45 |
| 5 | 252 |
| 6 | 1120 |
| 7 | 5270 |
| 8 | 23475 |
| 9 | 106950 |
| 10 | 483504 |
| 11 | 2211650 |
| 12 | 10148630 |
| 13 | 46911060 |
| 14 | 217863040 |
| 15 | 1017057256 |
| 16 | 4767774375 |
| 17 | 22438419120 |
| 18 | 105960830300 |
| 19 | 501928967930 |
| 20 | 2384170903140 |
| 21 | 11353241255900 |