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 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 20 |
| 6 | 70 |
| 7 | 255 |
| 8 | 959 |
| 9 | 3696 |
| 10 | 14520 |
| 11 | 57930 |
| 12 | 234080 |
| 13 | 955999 |
| 14 | 3939949 |
| 15 | 16364985 |
| 16 | 68437033 |
| 17 | 287910048 |
| 18 | 1217627176 |
| 19 | 5173854018 |
| 20 | 22077273858 |
| 21 | 94564541166 |
| 22 | 406451008386 |
| 23 | 1752472631360 |
| 24 | 7577758539846 |
| 25 | 32852955892191 |