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 | 15 |
| 6 | 30 |
| 7 | 70 |
| 8 | 210 |
| 9 | 462 |
| 10 | 6006 |
| 11 | 51051 |
| 12 | 102102 |
| 13 | 277134 |
| 14 | 6374082 |
| 15 | 10623470 |
| 16 | 223092870 |
| 17 | 588153930 |
| 18 | 18232771830 |
| 19 | 51893273670 |
| 20 | 2127624220470 |
| 21 | 5381637734130 |
| 22 | 252936973504110 |
| 23 | 6702829797858915 |
| 24 | 13405659595717830 |
| 25 | 41628100849860630 |
| 26 | 2539314151841498430 |
| 27 | 7397132529277408470 |