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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 6 |
| 5 | 24 |
| 6 | 360 |
| 7 | 2160 |
| 8 | 30240 |
| 9 | 241920 |
| 10 | 3628800 |
| 11 | 36288000 |
| 12 | 598752000 |
| 13 | 7185024000 |
| 14 | 130767436800 |
| 15 | 1830744115200 |
| 16 | 36614882304000 |
| 17 | 585838116864000 |
| 18 | 12804747411456000 |
| 19 | 230485453406208000 |
| 20 | 5474029518397440000 |
| 21 | 109480590367948800000 |
| 22 | 2810001819444019200000 |