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 | 3 |
| 4 | 6 |
| 5 | 30 |
| 6 | 120 |
| 7 | 840 |
| 8 | 3360 |
| 9 | 13440 |
| 10 | 134400 |
| 11 | 739200 |
| 12 | 6652800 |
| 13 | 86486400 |
| 14 | 778377600 |
| 15 | 16345929600 |
| 16 | 81729648000 |
| 17 | 1389404016000 |
| 18 | 12504636144000 |
| 19 | 79196028912000 |
| 20 | 1267136462592000 |
| 21 | 81096733605888000 |
| 22 | 3649353012264960000 |