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 | 6 |
| 2 | 30 |
| 3 | 148 |
| 4 | 755 |
| 5 | 4044 |
| 6 | 22841 |
| 7 | 136056 |
| 8 | 853452 |
| 9 | 5625950 |
| 10 | 38885297 |
| 11 | 281170080 |
| 12 | 2122313505 |
| 13 | 16688829122 |
| 14 | 136457754030 |
| 15 | 1158155642512 |
| 16 | 10186602918035 |
| 17 | 92711977180164 |
| 18 | 871936904575985 |
| 19 | 8462913158427580 |
| 20 | 84668764368102012 |
| 21 | 872196382566014506 |
| 22 | 9241557859113581689 |