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 | 2 |
| 3 | 9 |
| 4 | 68 |
| 5 | 730 |
| 6 | 10164 |
| 7 | 173838 |
| 8 | 3524688 |
| 9 | 82627200 |
| 10 | 2198295360 |
| 11 | 65431163160 |
| 12 | 2154106470240 |
| 13 | 77714083773456 |
| 14 | 3048821300491680 |
| 15 | 129221979665461200 |
| 16 | 5884296038166954240 |
| 17 | 286492923374605966080 |
| 18 | 14851359950834255500800 |