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 | 5 |
| 3 | 26 |
| 4 | 168 |
| 5 | 1195 |
| 6 | 8988 |
| 7 | 70318 |
| 8 | 566388 |
| 9 | 4665221 |
| 10 | 39113732 |
| 11 | 332691758 |
| 12 | 2863778072 |
| 13 | 24900264326 |
| 14 | 218372530380 |
| 15 | 1929363592870 |
| 16 | 17157018725000 |
| 17 | 153442147343648 |
| 18 | 1379250344938676 |
| 19 | 12453816724761706 |
| 20 | 112907775890596400 |
| 21 | 1027394297869071687 |