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 | 6 |
| 3 | 45 |
| 4 | 436 |
| 5 | 5305 |
| 6 | 78486 |
| 7 | 1372945 |
| 8 | 27760776 |
| 9 | 637267473 |
| 10 | 16372674730 |
| 11 | 465411092641 |
| 12 | 14501033559948 |
| 13 | 491388542871577 |
| 14 | 17991446425760094 |
| 15 | 707765586767260785 |
| 16 | 29770993461985724176 |
| 17 | 1333347150740094075169 |
| 18 | 63346656788618230928466 |