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 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 36 |
| 5 | 252 |
| 6 | 1260 |
| 7 | 5040 |
| 8 | 60480 |
| 9 | 786240 |
| 10 | 11793600 |
| 11 | 165110400 |
| 12 | 1651104000 |
| 13 | 18162144000 |
| 14 | 163459296000 |
| 15 | 1307674368000 |
| 16 | 31384184832000 |
| 17 | 784604620800000 |
| 18 | 21184324761600000 |
| 19 | 550792443801600000 |
| 20 | 16523773314048000000 |