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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 50 |
| 5 | 850 |
| 6 | 22100 |
| 7 | 817700 |
| 8 | 40885000 |
| 9 | 2657525000 |
| 10 | 217917050000 |
| 11 | 22009622050000 |
| 12 | 2685173890100000 |
| 13 | 389350214064500000 |
| 14 | 66189536390965000000 |
| 15 | 13039338669020105000000 |
| 16 | 2946890539198543730000000 |
| 17 | 757350868574025738610000000 |
| 18 | 219631751886467464196900000000 |