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) |
|---|---|
| 1 | 20 |
| 2 | 108 |
| 3 | 414 |
| 4 | 1936 |
| 5 | 9872 |
| 6 | 47732 |
| 7 | 229714 |
| 8 | 1134036 |
| 9 | 5624396 |
| 10 | 27808428 |
| 11 | 138043018 |
| 12 | 688575460 |
| 13 | 3440536326 |
| 14 | 17214566036 |
| 15 | 86312920760 |
| 16 | 433540643300 |
| 17 | 2180469363652 |
| 18 | 10980201879136 |
| 19 | 55360485999044 |
| 20 | 279418616308916 |
| 21 | 1411643137279198 |