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 | 3 |
| 2 | 24 |
| 3 | 201 |
| 4 | 1710 |
| 5 | 14649 |
| 6 | 125934 |
| 7 | 1084716 |
| 8 | 9353574 |
| 9 | 80711625 |
| 10 | 696756420 |
| 11 | 6016526145 |
| 12 | 51962422464 |
| 13 | 448833782556 |
| 14 | 3877191573720 |
| 15 | 33494487646632 |
| 16 | 289365173239302 |
| 17 | 2499947731531305 |
| 18 | 21598513018825920 |
| 19 | 186604716462810075 |
| 20 | 1612224571249844910 |