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 | 0 |
| 1 | 1 |
| 2 | 6 |
| 3 | 41 |
| 4 | 306 |
| 5 | 2426 |
| 6 | 20076 |
| 7 | 171481 |
| 8 | 1500666 |
| 9 | 13386206 |
| 10 | 121267476 |
| 11 | 1112674026 |
| 12 | 10318939956 |
| 13 | 96572168916 |
| 14 | 910896992856 |
| 15 | 8650566601401 |
| 16 | 82644968321226 |
| 17 | 793753763514806 |
| 18 | 7659535707782916 |
| 19 | 74225795172589006 |
| 20 | 722042370787826076 |