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 | 20 |
| 2 | 246 |
| 3 | 2408 |
| 4 | 20636 |
| 5 | 162288 |
| 6 | 1203000 |
| 7 | 8546208 |
| 8 | 58823919 |
| 9 | 395245708 |
| 10 | 2606333730 |
| 11 | 16933021560 |
| 12 | 108703640136 |
| 13 | 691068080928 |
| 14 | 4358220121296 |
| 15 | 27301946599872 |
| 16 | 170074452183570 |
| 17 | 1054434358722024 |
| 18 | 6510869338671852 |
| 19 | 40063301434583504 |
| 20 | 245781459952640040 |