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 | 4 |
| 3 | 18 |
| 4 | 92 |
| 5 | 505 |
| 6 | 2922 |
| 7 | 17541 |
| 8 | 108270 |
| 9 | 682823 |
| 10 | 4380942 |
| 11 | 28504466 |
| 12 | 187636994 |
| 13 | 1247375147 |
| 14 | 8362420498 |
| 15 | 56471709841 |
| 16 | 383790966537 |
| 17 | 2622982116829 |
| 18 | 18016055333571 |
| 19 | 124296340608870 |
| 20 | 860986586024343 |
| 21 | 5985590694574930 |
| 22 | 41749023026002831 |