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 | 4 |
| 3 | 18 |
| 4 | 83 |
| 5 | 387 |
| 6 | 1815 |
| 7 | 8541 |
| 8 | 40276 |
| 9 | 190182 |
| 10 | 898844 |
| 11 | 4250780 |
| 12 | 20111394 |
| 13 | 95181166 |
| 14 | 450565602 |
| 15 | 2133227418 |
| 16 | 10101126723 |
| 17 | 47834649675 |
| 18 | 226540406571 |
| 19 | 1072931019393 |
| 20 | 5081776592061 |
| 21 | 24069823974879 |
| 22 | 114009427284309 |