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 | 2 |
| 3 | 3 |
| 4 | 9 |
| 5 | 70 |
| 6 | 117 |
| 7 | 503 |
| 8 | 648 |
| 9 | 1078 |
| 10 | 12868 |
| 11 | 41235 |
| 12 | 178650 |
| 13 | 377670 |
| 14 | 394301 |
| 15 | 546185 |
| 16 | 2600672 |
| 17 | 8729780 |
| 18 | 41318679 |
| 19 | 83367169 |
| 20 | 525961060 |
| 21 | 561571346 |
| 22 | 1556964264 |
| 23 | 1868773845 |
| 24 | 15139200289 |
| 25 | 27297789005 |
| 26 | 30324107039 |
| 27 | 56699922000 |