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 | 4 |
| 2 | 25 |
| 3 | 197 |
| 4 | 1745 |
| 5 | 16580 |
| 6 | 165115 |
| 7 | 1700809 |
| 8 | 17971466 |
| 9 | 193710087 |
| 10 | 2121585340 |
| 11 | 23543198588 |
| 12 | 264138223362 |
| 13 | 2991130956918 |
| 14 | 34143543312267 |
| 15 | 392458689992396 |
| 16 | 4538574332686469 |
| 17 | 52768896995910303 |
| 18 | 616471818881678085 |
| 19 | 7232838546289017796 |
| 20 | 85188401983572928395 |