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 | 6 |
| 3 | 135 |
| 4 | 5052 |
| 5 | 264270 |
| 6 | 17765100 |
| 7 | 1459311840 |
| 8 | 141655066560 |
| 9 | 15864853936680 |
| 10 | 2013630348265200 |
| 11 | 285637924882787400 |
| 12 | 44782566595855149600 |
| 13 | 7689608275439667376800 |
| 14 | 1435181273959520911824000 |
| 15 | 289287240571642427530416000 |
| 16 | 62630090604946453360419648000 |