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 | 0 |
| 1 | 1 |
| 2 | 5 |
| 3 | 30 |
| 4 | 199 |
| 5 | 1355 |
| 6 | 9276 |
| 7 | 63565 |
| 8 | 435665 |
| 9 | 2986074 |
| 10 | 20466835 |
| 11 | 140281751 |
| 12 | 961505400 |
| 13 | 6590256025 |
| 14 | 45170286749 |
| 15 | 309601751190 |
| 16 | 2122041971551 |
| 17 | 14544692049635 |
| 18 | 99690802375860 |
| 19 | 683290924581349 |
| 20 | 4683345669693545 |