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 | 4 |
| 3 | 18 |
| 4 | 94 |
| 5 | 529 |
| 6 | 3135 |
| 7 | 19270 |
| 8 | 121732 |
| 9 | 785496 |
| 10 | 5155167 |
| 11 | 34304706 |
| 12 | 230923653 |
| 13 | 1569684910 |
| 14 | 10759159000 |
| 15 | 74281473504 |
| 16 | 516089542684 |
| 17 | 3605685460750 |
| 18 | 25316226436086 |
| 19 | 178538289189108 |
| 20 | 1264131169628799 |
| 21 | 8982889404251721 |
| 22 | 64041351551534215 |