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 | 1 |
| 2 | 5 |
| 3 | 28 |
| 4 | 209 |
| 5 | 1826 |
| 6 | 18217 |
| 7 | 203106 |
| 8 | 2487361 |
| 9 | 33077566 |
| 10 | 473318201 |
| 11 | 7234847126 |
| 12 | 117435618577 |
| 13 | 2014339775800 |
| 14 | 36360190887217 |
| 15 | 688237505878726 |
| 16 | 13618646813974785 |
| 17 | 280960214041690038 |
| 18 | 6028928694559721305 |
| 19 | 134277542969681115870 |
| 20 | 3098232871805383942801 |