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 | 2 |
| 2 | 7 |
| 3 | 28 |
| 4 | 119 |
| 5 | 524 |
| 6 | 2363 |
| 7 | 10844 |
| 8 | 50446 |
| 9 | 237280 |
| 10 | 1126437 |
| 11 | 5389916 |
| 12 | 25967972 |
| 13 | 125868952 |
| 14 | 613385075 |
| 15 | 3003586196 |
| 16 | 14771851093 |
| 17 | 72936101780 |
| 18 | 361419276386 |
| 19 | 1796837068400 |
| 20 | 8960207761500 |