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 | 2 |
| 2 | 5 |
| 3 | 15 |
| 4 | 50 |
| 5 | 175 |
| 6 | 625 |
| 7 | 2251 |
| 8 | 8142 |
| 9 | 29544 |
| 10 | 107538 |
| 11 | 392726 |
| 12 | 1439204 |
| 13 | 5292833 |
| 14 | 19533241 |
| 15 | 72333107 |
| 16 | 268728214 |
| 17 | 1001448308 |
| 18 | 3742866166 |
| 19 | 14026901282 |
| 20 | 52701685564 |
| 21 | 198481560878 |
| 22 | 749170991770 |
| 23 | 2833635556670 |
| 24 | 10738689128460 |
| 25 | 40770816357920 |
| 26 | 155056284790340 |
| 27 | 590644481896972 |